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The Top 10 Science Experiments of All Time

These seminal experiments changed our understanding of the universe and ourselves..

Every day, we conduct science experiments, posing an “if” with a “then” and seeing what shakes out. Maybe it’s just taking a slightly different route on our commute home or heating that burrito for a few seconds longer in the microwave. Or it could be trying one more variation of that gene, or wondering what kind of code would best fit a given problem. Ultimately, this striving, questioning spirit is at the root of our ability to discover anything at all. A willingness to experiment has helped us delve deeper into the nature of reality through the pursuit we call science. 

A select batch of these science experiments has stood the test of time in showcasing our species at its inquiring, intelligent best. Whether elegant or crude, and often with a touch of serendipity, these singular efforts have delivered insights that changed our view of ourselves or the universe. 

Here are nine such successful endeavors — plus a glorious failure — that could be hailed as the top science experiments of all time.

Eratosthenes Measures the World

Experimental result: The first recorded measurement of Earth’s circumference 

When: end of the third century B.C.

Just how big is our world? Of the many answers from ancient cultures, a stunningly accurate value calculated by Eratosthenes has echoed down the ages. Born around 276 B.C. in Cyrene, a Greek settlement on the coast of modern-day Libya, Eratosthenes became a voracious scholar — a trait that brought him both critics and admirers. The haters nicknamed him Beta, after the second letter of the Greek alphabet. University of Puget Sound physics professor James Evans explains the Classical-style burn: “Eratosthenes moved so often from one field to another that his contemporaries thought of him as only second-best in each of them.” Those who instead celebrated the multitalented Eratosthenes dubbed him Pentathlos, after the five-event athletic competition.

That mental dexterity landed the scholar a gig as chief librarian at the famous library in Alexandria, Egypt. It was there that he conducted his famous experiment. He had heard of a well in Syene, a Nile River city to the south (modern-day Aswan), where the noon sun shone straight down, casting no shadows, on the date of the Northern Hemisphere’s summer solstice. Intrigued, Eratosthenes measured the shadow cast by a vertical stick in Alexandria on this same day and time. He determined the angle of the sun’s light there to be 7.2 degrees, or 1/50th of a circle’s 360 degrees. 

Knowing — as many educated Greeks did — Earth was spherical, Eratosthenes fathomed that if he knew the distance between the two cities, he could multiply that figure by 50 and gauge Earth’s curvature, and hence its total circumference. Supplied with that information, Eratosthenes deduced Earth’s circumference as 250,000 stades, a Hellenistic unit of length equaling roughly 600 feet. The span equates to about 28,500 miles, well within the ballpark of the correct figure of 24,900 miles. 

Eratosthenes’ motive for getting Earth’s size right was his keenness for geography, a field whose name he coined. Fittingly, modernity has bestowed upon him one more nickname: father of geography. Not bad for a guy once dismissed as second-rate.

William Harvey Takes the Pulse of Nature

Experimental result: The discovery of blood circulation

When: Theory published in 1628

Boy, was Galen wrong. 

The Greek physician-cum-philosopher proposed a model of blood flow in the second century that, despite being full of whoppers, prevailed for nearly 1,500 years. Among its claims: The liver constantly makes new blood from food we eat; blood flows throughout the body in two separate streams, one infused (via the lungs) with “vital spirits” from air; and the blood that tissues soak up never returns to the heart. 

Overturning all this dogma took a series of often gruesome experiments. 

High-born in England in 1578, William Harvey rose to become royal physician to King James I, affording him the time and means to pursue his greatest interest: anatomy. He first hacked away (literally, in some cases) at the Galenic model by exsanguinating — draining the blood from — test critters, including sheep and pigs. Harvey realized that if Galen were right, an impossible volume of blood, exceeding the animals’ size, would have to pump through the heart every hour. 

To drive this point home, Harvey sliced open live animals in public, demonstrating their puny blood supplies. He also constricted blood flow into a snake’s exposed heart by finger-pinching a main vein. The heart shrunk and paled; when pierced, it poured forth little blood. By contrast, choking off the main exiting artery swelled the heart. Through studies of the slow heart beats of reptiles and animals near death, he discerned the heart’s contractions, and deduced that it pumped blood through the body in a circuit.

According to Andrew Gregory, a professor of history and philosophy of science at University College London, this was no easy deduction on Harvey’s part. “If you look at a heart beating normally in its normal surroundings, it is very difficult to work out what is actually happening,” he says. 

Experiments with willing people, which involved temporarily blocking blood flow in and out of limbs, further bore out Harvey’s revolutionary conception of blood circulation. He published the full theory in a 1628 book, De Motu Cordis [The Motion of the Heart]. His evidence-based approach transformed medical science, and he’s recognized today as the father of modern medicine and physiology.

Gregor Mendel Cultivates Genetics

Experimental result: The fundamental rules of genetic inheritance 

When: 1855-1863 

A child, to varying degrees, resembles a parent, whether it’s a passing resemblance or a full-blown mini-me. Why? 

The profound mystery behind the inheritance of physical traits began to unravel a century and a half ago, thanks to Gregor Mendel. Born in 1822 in what is now the Czech Republic, Mendel showed a knack for the physical sciences, though his farming family had little money for formal education. Following the advice of a professor, he joined the Augustinian order, a monastic group that emphasized research and learning, in 1843. 

Ensconced at a monastery in Brno, the shy Gregor quickly began spending time in the garden. Fuchsias in particular grabbed his attention, their daintiness hinting at an underlying grand design. “The fuchsias probably gave him the idea for the famous experiments,” says Sander Gliboff, who researches the history of biology at Indiana University Bloomington. “He had been crossing different varieties, trying to get new colors or combinations of colors, and he got repeatable results that suggested some law of heredity at work.”

These laws became clear with his cultivation of pea plants. Using paintbrushes, Mendel dabbed pollen from one to another, precisely pairing thousands of plants with certain traits over a stretch of about seven years. He meticulously documented how matching yellow peas and green peas, for instance, always yielded a yellow plant. Yet mating these yellow offspring together produced a generation where a quarter of the peas gleamed green again. Ratios like these led to Mendel’s coining of the terms dominant (the yellow color, in this case) and recessive for what we now call genes, and which Mendel referred to as “factors.” 

He was ahead of his time. His studies received scant attention in their day, but decades later, when other scientists discovered and replicated Mendel’s experiments, they came to be regarded as a breakthrough. 

“The genius in Mendel’s experiments was his way of formulating simple hypotheses that explain a few things very well, instead of tackling all the complexities of heredity at once,” says Gliboff. “His brilliance was in putting it all together into a project that he could actually do.”

Isaac Newton Eyes Optics

Experimental result: The nature of color and light

When: 1665-1666

Before he was that Isaac Newton — scientist extraordinaire and inventor of the laws of motion, calculus and universal gravitation (plus a crimefighter to boot) — plain ol’ Isaac found himself with time to kill. To escape a devastating outbreak of plague in his college town of Cambridge, Newton holed up at his boyhood home in the English countryside. There, he tinkered with a prism he picked up at a local fair — a “child’s plaything,” according to Patricia Fara, fellow of Clare College, Cambridge. 

Let sunlight pass through a prism and a rainbow, or spectrum, of colors splays out. In Newton’s time, prevailing thinking held that light takes on the color from the medium it transits, like sunlight through stained glass. Unconvinced, Newton set up a prism experiment that proved color is instead an inherent property of light itself. This revolutionary insight established the field of optics, fundamental to modern science and technology. 

Newton deftly executed the delicate experiment: He bored a hole in a window shutter, allowing a single beam of sunlight to pass through two prisms. By blocking some of the resulting colors from reaching the second prism, Newton showed that different colors refracted, or bent, differently through a prism. He then singled out a color from the first prism and passed it alone through the second prism; when the color came out unchanged, it proved the prism didn’t affect the color of the ray. The medium did not matter. Color was tied up, somehow, with light itself. 

Partly owing to the ad hoc, homemade nature of Newton’s experimental setup, plus his incomplete descriptions in a seminal 1672 paper, his contemporaries initially struggled to replicate the results. “It’s a really, really technically difficult experiment to carry out,” says Fara. “But once you have seen it, it’s incredibly convincing.” 

In making his name, Newton certainly displayed a flair for experimentation, occasionally delving into the self-as-subject variety. One time, he stared at the sun so long he nearly went blind. Another, he wormed a long, thick needle under his eyelid, pressing on the back of his eyeball to gauge how it affected his vision. Although he had plenty of misses in his career — forays into occultism, dabbling in biblical numerology — Newton’s hits ensured his lasting fame.

Michelson and Morley Whiff on Ether

Experimental result: The way light moves

Say “hey!” and the sound waves travel through a medium (air) to reach your listener’s ears. Ocean waves, too, move through their own medium: water. Light waves are a special case, however. In a vacuum, with all media such as air and water removed, light somehow still gets from here to there. How can that be? 

The answer, according to the physics en vogue in the late 19th century, was an invisible, ubiquitous medium delightfully dubbed the “luminiferous ether.” Working together at what is now Case Western Reserve University in Ohio, Albert Michelson and Edward W. Morley set out to prove this ether’s existence. What followed is arguably the most famous failed experiment in history. 

The scientists’ hypothesis was thus: As Earth orbits the sun, it constantly plows through ether, generating an ether wind. When the path of a light beam travels in the same direction as the wind, the light should move a bit faster compared with sailing against the wind. 

To measure the effect, miniscule though it would have to be, Michelson had just the thing. In the early 1880s, he had invented a type of interferometer, an instrument that brings sources of light together to create an interference pattern, like when ripples on a pond intermingle. A Michelson interferometer beams light through a one-way mirror. The light splits in two, and the resulting beams travel at right angles to each other. After some distance, they reflect off mirrors back toward a central meeting point. If the light beams arrive at different times, due to some sort of unequal displacement during their journeys (say, from the ether wind), they create a distinctive interference pattern. 

The researchers protected their delicate interferometer setup from vibrations by placing it atop a solid sandstone slab, floating almost friction-free in a trough of mercury and further isolated in a campus building’s basement. Michelson and Morley slowly rotated the slab, expecting to see interference patterns as the light beams synced in and out with the ether’s direction. 

Instead, nothing. Light’s speed did not vary. 

Neither researcher fully grasped the significance of their null result. Chalking it up to experimental error, they moved on to other projects. (Fruitfully so: In 1907, Michelson became the first American to win a Nobel Prize, for optical instrument-based investigations.) But the huge dent Michelson and Morley unintentionally kicked into ether theory set off a chain of further experimentation and theorizing that led to Albert Einstein’s 1905 breakthrough new paradigm of light, special relativity.

Marie Curie’s Work Matters

Experimental result: Defining radioactivity 

Few women are represented in the annals of legendary scientific experiments, reflecting their historical exclusion from the discipline. Marie Sklodowska broke this mold. 

Born in 1867 in Warsaw, she immigrated to Paris at age 24 for the chance to further study math and physics. There, she met and married physicist Pierre Curie, a close intellectual partner who helped her revolutionary ideas gain a foothold within the male-dominated field. “If it wasn’t for Pierre, Marie would never have been accepted by the scientific community,” says Marilyn B. Ogilvie, professor emeritus in the history of science at the University of Oklahoma. “Nonetheless, the basic hypotheses — those that guided the future course of investigation into the nature of radioactivity — were hers.”

The Curies worked together mostly out of a converted shed on the college campus where Pierre worked. For her doctoral thesis in 1897, Marie began investigating a newfangled kind of radiation, similar to X-rays and discovered just a year earlier. Using an instrument called an electrometer, built by Pierre and his brother, Marie measured the mysterious rays emitted by thorium and uranium. Regardless of the elements’ mineralogical makeup — a yellow crystal or a black powder, in uranium’s case — radiation rates depended solely on the amount of the element present. 

From this observation, Marie deduced that the emission of radiation had nothing to do with a substance’s molecular arrangements. Instead, radioactivity — a term she coined — was an inherent property of individual atoms, emanating from their internal structure. Up until this point, scientists had thought atoms elementary, indivisible entities. Marie had cracked the door open to understanding matter at a more fundamental, subatomic level. 

Curie was the first woman to win a Nobel Prize, in 1903, and one of a very select few people to earn a second Nobel, in 1911 (for her later discoveries of the elements radium and polonium). 

“In her life and work,” says Ogilvie, “she became a role model for young women who wanted a career in science.”

Ivan Pavlov Salivates at the Idea

Experimental result: The discovery of conditioned reflexes

When: 1890s-1900s

Russian physiologist Ivan Pavlov scooped up a Nobel Prize in 1904 for his work with dogs, investigating how saliva and stomach juices digest food. While his scientific legacy will always be tied to doggie drool, it is the operations of the mind — canine, human and otherwise — for which Pavlov remains celebrated today.

Gauging gastric secretions was no picnic. Pavlov and his students collected the fluids that canine digestive organs produced, with a tube suspended from some pooches’ mouths to capture saliva. Come feeding time, the researchers began noticing that dogs who were experienced in the trials would start drooling into the tubes before they’d even tasted a morsel. Like numerous other bodily functions, the generation of saliva was considered a reflex at the time, an unconscious action only occurring in the presence of food. But Pavlov’s dogs had learned to associate the appearance of an experimenter with meals, meaning the canines’ experience had conditioned their physical responses. 

“Up until Pavlov’s work, reflexes were considered fixed or hardwired and not changeable,” says Catharine Rankin, a psychology professor at the University of British Columbia and president of the Pavlovian Society. “His work showed that they could change as a result of experience.” 

Pavlov and his team then taught the dogs to associate food with neutral stimuli as varied as buzzers, metronomes, rotating objects, black squares, whistles, lamp flashes and electric shocks. Pavlov never did ring a bell, however; credit an early mistranslation of the Russian word for buzzer for that enduring myth. 

The findings formed the basis for the concept of classical, or Pavlovian, conditioning. It extends to essentially any learning about stimuli, even if reflexive responses are not involved. “Pavlovian conditioning is happening to us all of the time,” says W. Jeffrey Wilson of Albion College, fellow officer of the Pavlovian Society. “Our brains are constantly connecting things we experience together.” In fact, trying to “un-wire” these conditioned responses is the strategy behind modern treatments for post-traumatic stress disorder, as well as addiction.

Robert Millikan Gets a Charge

Experimental result: The precise value of a single electron’s charge

By most measures, Robert Millikan had done well for himself. Born in 1868 in a small town in Illinois, he went on to earn degrees from Oberlin College and Columbia University. He studied physics with European luminaries in Germany. He then joined the University of Chicago’s physics department, and even penned some successful textbooks. 

But his colleagues were doing far more. The turn of the 20th century was a heady time for physics: In the span of just over a decade, the world was introduced to quantum physics, special relativity and the electron — the first evidence that atoms had divisible parts. By 1908, Millikan found himself pushing 40 without a significant discovery to his name. 

The electron, though, offered an opportunity. Researchers had struggled with whether the particle represented a fundamental unit of electric charge, the same in all cases. It was a critical determination for further developing particle physics. With nothing to lose, Millikan gave it a go. 

In his lab at the University of Chicago, he began working with containers of thick water vapor, called cloud chambers, and varying the strength of an electric field within them. Clouds of water droplets formed around charged atoms and molecules before descending due to gravity. By adjusting the strength of the electric field, he could slow down or even halt a single droplet’s fall, countering gravity with electricity. Find the precise strength where they balanced, and — assuming it did so consistently — that would reveal the charge’s value. 

When it turned out water evaporated too quickly, Millikan and his students — the often-unsung heroes of science — switched to a longer-lasting substance: oil, sprayed into the chamber by a drugstore perfume atomizer. 

The increasingly sophisticated oil-drop experiments eventually determined that the electron did indeed represent a unit of charge. They estimated its value to within whiskers of the currently accepted charge of one electron (1.602 x 10-19 coulombs). It was a coup for particle physics, as well as Millikan. 

“There’s no question that it was a brilliant experiment,” says Caltech physicist David Goodstein. “Millikan’s result proved beyond reasonable doubt that the electron existed and was quantized with a definite charge. All of the discoveries of particle physics follow from that.”

Young, Davisson and Germer See Particles Do the Wave

Experimental result: The wavelike nature of light and electrons 

When: 1801 and 1927, respectively 

Light: particle or wave? Having long wrestled with this seeming either/or, many physicists settled on particle after Isaac Newton’s tour de force through optics. But a rudimentary, yet powerful, demonstration by fellow Englishman Thomas Young shattered this convention. 

Young’s interests covered everything from Egyptology (he helped decode the Rosetta Stone) to medicine and optics. To probe light’s essence, Young devised an experiment in 1801. He cut two thin slits into an opaque object, let sunlight stream through them and watched how the beams cast a series of bright and dark fringes on a screen beyond. Young reasoned that this pattern emerged from light wavily spreading outward, like ripples across a pond, with crests and troughs from different light waves amplifying and canceling each other. 

Although contemporary physicists initially rebuffed Young’s findings, rampant rerunning of these so-called double-slit experiments established that the particles of light really do move like waves. “Double-slit experiments have become so compelling [because] they are relatively easy to conduct,” says David Kaiser, a professor of physics and of the history of science at MIT. “There is an unusually large ratio, in this case, between the relative simplicity and accessibility of the experimental design and the deep conceptual significance of the results.”

More than a century later, a related experiment by Clinton Davisson and Lester Germer showed the depth of this significance. At what is now called Nokia Bell Labs in New Jersey, the physicists ricocheted electron particles off a nickel crystal. The scattered electrons interacted to produce a pattern only possible if the particles also acted like waves. Subsequent double slit-style experiments with electrons proved that particles with matter and undulating energy (light) can each act like both particles and waves. The paradoxical idea lies at the heart of quantum physics, which at the time was just beginning to explain the behavior of matter at a fundamental level. 

“What these experiments show, at their root, is that the stuff of the world, be it radiation or seemingly solid matter, has some irreducible, unavoidable wavelike characteristics,” says Kaiser. “No matter how surprising or counterintuitive that may seem, physicists must take that essential ‘waviness’ into account.”

Robert Paine Stresses Starfish

Experimental result: The disproportionate impact of keystone species on ecosystems

When: Initially presented in a 1966 paper

Just like the purple starfish he crowbarred off rocks and chucked into the Pacific Ocean, Bob Paine threw conventional wisdom right out the window. 

By the 1960s, ecologists had come to agree that habitats thrived primarily through diversity. The common practice of observing these interacting webs of creatures great and small suggested as much. Paine took a different approach. 

Curious what would happen if he intervened in an environment, Paine ran his starfish-banishing experiments in tidal pools along and off the rugged coast of Washington state. The removal of this single species, it turned out, could destabilize a whole ecosystem. Unchecked, the starfish’s barnacle prey went wild — only to then be devoured by marauding mussels. These shellfish, in turn, started crowding out the limpets and algal species. The eventual result: a food web in tatters, with only mussel-dominated pools left behind. 

Paine dubbed the starfish a keystone species, after the necessary center stone that locks an arch into place. A revelatory concept, it meant that all species do not contribute equally in a given ecosystem. Paine’s discovery had a major influence on conservation, overturning the practice of narrowly preserving an individual species for the sake of it, versus an ecosystem-based management strategy.

“His influence was absolutely transformative,” says Oregon State University’s Jane Lubchenco, a marine ecologist. She and her husband, fellow OSU professor Bruce Menge, met 50 years ago as graduate students in Paine’s lab at the University of Washington. Lubchenco, the administrator of the National Oceanic Atmospheric Administration from 2009 to 2013, saw over the years the impact that Paine’s keystone species concept had on policies related to fisheries management.

Lubchenco and Menge credit Paine’s inquisitiveness and dogged personality for changing their field. “A thing that made him so charismatic was almost a childlike enthusiasm for ideas,” says Menge. “Curiosity drove him to start the experiment, and then he got these spectacular results.”

Paine died in 2016. His later work had begun exploring the profound implications of humans as a hyper-keystone species, altering the global ecosystem through climate change and unchecked predation.

Adam Hadhazy is based in New Jersey. His work has also appeared in New Scientist and Popular Science , among other publications. This story originally appeared in print as "10 Experiments That Changed Everything"

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• Activities for Kids

49 Science Experiments for Kids to Try at Home

Looking for science experiments for kids? Thanks to common household ingredients, some ingenuity, and our guide, these at-home science experiments for kids make any day exciting. To help you prepare, we’ve rated each experiment from one to five sponges so you know the messiness factor ahead of time. If you’re looking for seasonal projects, check out these water-themed science experiments . Or how about a few science projects for kids that are perfect for the backyard ?

TIP: Did you know there are a ton of awesome science kits and subscription boxes that will further develop your child’s love of science? KiwiCrate is one of our favorite ed-tech companies, as they offer seriously fun & enriching science & art projects, for kids 0 months up to 13+.

Classic Science Experiments for Kids

Potato battery science experiment.

A lesson in: Chemical to electrical energy

When these nails and copper wires collide, heat is generated (psst ... heat is a result of expended energy, so you can explain to your little runner why he feels warmer after a race around the house). But with some potato magic, the properties of the nail and copper stay separated, allowing the heat to become the electric energy needed to power up your devices. Build your own potato battery with this tutorial from Wiki How .

Messiness factor: One sponge

Make a Baking Soda & Vinegar "Steam" Powered Boat

A lesson in: Chemical reactions

Sure, anyone can do the old baking soda and vinegar volcano, but what about creating a boat that is propelled by this classic chemical reaction ? Keep your little Einsteins busy this afternoon with this cool science project for kids that doesn't require a lot of prep. 

Messiness factor: Three sponges

Make Water Float

A lesson in: Air pressure

Can you make water float? We bet you can. No, you don’t need to be a wizard or a witch. You don’t need to cast a spell. There’s nothing magic about it at all, in fact. You can make water float using science. The “trick” to this experiment is air pressure. Get everything you need and the how-to, right here , thanks to Mike Adamick and his book, Dad's Book of Awesome Science Experiments .

Messiness factor: Two sponges

Photo by Mike Adamick. Copyright © 2014 F+W Media, Inc. Used by permission of the publisher. All rights reserved.

Germ Testing Science Project for Kids

A lesson in: Germs

This germ-growing science project for kids will help them understand how even the cleanest-looking surfaces (and hands) can be filled with germs, is one of the easiest science experiments for kids we've found. Get the fun and yucky instructions at Kids Activity Blog .

Make an Edible Water Bottle

View this post on Instagram A post shared by Zar🐴 🦜Travel Fun (@chasing_ice88)

A lesson in: Chemistry and specifically, spherification.

This futuristic science experiment will leave your kids wanting to know more about chemistry. Quench her thirst for knowledge when you create an edible membrane around teaspoons of water to make these handy water “bottles.” The tutorial is in video form over at Inhabitat.  Trust us, it’s as cool as it looks!

Messiness factor: One sponge.

Make Crystal Egg Geodes

View this post on Instagram A post shared by STEM Girls | Fun Learning STEM (@brownstemgirls)

A lesson in: Molecular bonding and chemistry.

This grow-your-own experiment lets you grow crystals inside an eggshell. Be sure to get alum powder that contains potassium, or else you won’t get any crystal growth. Adding drops of food dye to the growing solution yields some super cool crystals. A perfectly formed geode takes about 12-15 hours to grow, making this a great weekend project. Get the tutorial for this science experiment for kids at Art and Soul.

Messiness factor: Four sponges.

Check the Iron in Breakfast Cereal

View this post on Instagram A post shared by Kimberly Scott (@kimberlyscottscience)

A lesson in: Magnetism.

You’ve probably seen the label that says “fortified with iron” on your cereal box, but how much iron is actually in your cereal? Is there enough to cause a magnetic reaction? This super easy experiment doesn’t require too many fancy ingredients (cereal + magnet) which means you and the kiddos can try it right away. The results may surprise you! Get the how-to at Rookie Parenting and get started!

Messiness Factor: Two sponges.

Learn About Shooting Stars

A lesson in: Astronomy

With this fun video from They Might Be Giants , kids can learn that shooting stars are not stars, they're meteorites. Then, take it out back for a fun backyard stargazing session. We love this science experiment you can do at home! 

Messiness Factor: One sponge

Related:  14 Backyard Science Experiments for Kids

Marshmallow Tower

A lesson in: Engineering

Using only marshmallows and dry spaghetti noodles, kids can experiment with structure, stability, and weight distribution. Get the instructions from Kesler Science by clicking here.  

Messiness factor : 1 sponge

Paper Airplane Science

A lesson in: Aerodynamics

By making various paper airplanes , your scientists can test the drag of each plane, which will have an effect on how far they fly. Get more info on this science project for kids here .

Messiness factor: 1 sponge

Walk on Eggs

A lesson in: Weight distribution

How can you walk on eggs without breaking them? Steve Spengler shows us how and teaches an awesome lesson on how an egg’s unique shape gives it tremendous strength, despite its seeming fragility. Check out this easy science experiment for kids to get started.

Messiness factor: 1-3 sponges, depending on the state of the eggs in the end!

A Lesson in: Molecules

Fill a shallow dish with milk, drop food coloring, and make sure the drops don't touch. Then, dip a cotton swab in dish soap and place it in the middle of the dish. The colors will begin to swirl and seem as though they are moving on their own! Explain to your kids that the soap reduces surface tension and makes the fat molecules in the milk move. Click here for more science experiments that use food coloring.

Messiness Factor: 2 sponges

Professor Egghead's Lesson about Light

A Lesson in : Light

Learn all about the sun and what it gives humans (think energy and warmth!) You'll also do an experiment to learn about different kinds of light, even ultraviolet rays. Get the video from Professor Egghead here.  

Messiness factor: 1 sponge 

Cup Amplifier

A lesson in: Sound

Slide a mobile phone into this low-tech amplifier and the result will be music to your ears. The audio is deeper, richer, and louder, thanks to the science of sound waves and the natural amplification created by the cone-shaped cups. If the two cups look a bit like the attentive ears of a cat or fox, that’s no coincidence. Animal ears use the same science, but in reverse: they help creatures hear by gathering sound waves and directing them into the ear. For engineers, that’s a design worth copying.

Customize your amplifier to fit any size phone!

Tabs cut all around the hold make it easy to glue the cardboard tube in place.

Cut a slot with a flap to support your phone.

What’s Going On The Cup Amplifier focuses and projects sound waves, in the same way that a cheerleader’s megaphone (or even just your cupped hands) amplifies your voice. Once sound waves are created, they want to spread out in all directions. The amplifier directs them from your phone’s speakers into the cardboard cups, where, instead of scattering, they are gathered and channeled in one direction—out the openings.

Excerpted from  Cardboard Box Engineering  © 2020 by Jonathan Adolph. Used with permission from Storey Publishing.

Skittles Science

A Lesson in: Stratification

A great way to get rid of extra candy, this easy science experiment for kids uses Skittles and whatever liquids you want to use. The idea is, the candy is made of ingredients that dissolve, so kids get a chance to guess which liquid will make the Skittles dissolve the fastest. Get more info over at Little Bins for Little Hands . 

Find Out How Many Water Drops Fit on a Coin

A Lesson in: Chemistry

An easy science experiment to do at home is one that helps kids find out what affects the surface tension of water! You'll need basic materials like a penny and a water dropper, and be sure to make a hypothesis before you start. You might be surprised! Get the tutorial from Rookie Parenting . 

Pulley Experiment

A Lesson in: Physics

This simple experiment requires a trip to the hardware store, but putting it all together is a cinch. Once you've completed the system, have your kids pick up different-sized rocks and make a note about how difficult it is. Then, try with the pulley. Is it easier or is it harder? To find out how to make your pulley, and for other questions to ask your kids, head over to Little Bins for Little Hands . 

Make a Volcano Explode

A Lesson in: Chemical reactions

There's a reason why this science experiment is so popular. When the solid baking soda (sodium bicarbonate—a base) mixes with the liquid vinegar (acetic acid—a weak acid), it creates a gas—carbon dioxide! Besides the chemical reaction, kids enjoy making the actual volcano, whether it's out of clay, mud, or foam sheets. Get a great step-by-step tutorial from The Dad’s Book of Awesome Science Experiments by clicking here . 

Messiness Factor: Four sponges

Bake Hygroscopic Cookies

A Lesson in: Hygroscopy. 

This simple science experiment is best when you check in on it the next morning. Bake up a batch of cookies, then place them in an airtight container with a piece of fresh bread. Watch as the cookies stay straight-from-the-oven soft thanks to the moisture of the bread (The sugar in the cookies is hygroscopic, which means it absorbs water molecules out of the bread). The best part? Getting to eat the cookies!

The Juice-Tasting Challenge

A lesson in : Taste buds and olfactory senses.

Tummy’s rumbling–it’s time to eat! Did you know that you “eat” with your nose and eyes as well as your mouth? It’s true. Put your family’s sense of smell and sight to the test with this juice-guessing game.

You’ll Need: Masking tape 4 glasses Pen and paper 4 flavors of juice 4 food colorings

How to: 1. Stack a piece of tape on the bottom of each glass and number them one to four, making sure your partner can’t see the numbers. Pour one type of juice into each glass.

2. Send your partner out of the room. Drip a different food coloring into each juice and stir so your partner can’t recognize the juice by its color alone. Record the number, juice type, and color in each glass on a piece of paper.

3. Call your partner back. Tell her to hold her nose, sip from each glass, and guess the juice If she’s like most people, she’ll be kind of confused–her eyes and tongue give her two conflicting flavor messages.

4. Ask her to unplug her nose, close her eyes, and sniff the juice before drinking it. Her guesses should be on target now. All hail the mighty schnoz!

Reprinted from  Exploralab: 150+ Ways to Investigate the Amazing Science All Around You . 

Messiness factor: One sponge. 

Experiment with Tie Dye

A lesson in: Chemistry.

Dyes are fiber reactive, so there's a chemical reaction between the dye and the fabric. You can do this experiment with everything from paper to t-shirts. We've got a great list of tie-dye projects here . 

Messiness Factor : Five sponges.

Make a Sundial

View this post on Instagram A post shared by Jennifer Carter (@_thebestkindofchaos_)

Unravel the mysteries of time. Or at least figure out the basics by setting up a sundial outside . Take time each hour to check the sun’s positioning and make note of it so your sidekick can see the bigger picture.

Messiness Factor : One sponge

Dry Ice Bubbles

A lesson in: Gas.

Dry ice is already cool enough on its own, but it takes science to turn them into bubbles. When you add water, it changes the temperature of the dry ice, causing the ice to go from solid to gas. That’s where the fog and bubbles come from! Head to Simply Modern Mom to get the full tutorial. But be careful: Dry ice can cause serious skin burns, so make sure your kids are well-supervised and know not to touch the ice.

Messiness factor: Three sponges.

Invisible Licorice

A lesson in : Light and perspective.

Did the candy melt or disappear? Your sweetums might think it’s magic, but it’s really all about how oil redirects light, causing half the candy to disappear! Click here for the instructions on how to recreate this mind-warping experiment.

Egg in a Bottle

Your whistler has the basics of air pressure down just by using their mouth to blow. And now you can amaze them with this science experiment for kids. There is a little fire play involved (dropping a lit paper into the bottle), but that’s what causes the unbalanced air pressure, which pushes the egg into the bottle. Want to test it out? Head over to Steve Spangler Science for the tutorial.

Invisible Ink

A lesson in: Oxidation.

If your snacker has noticed how their apples have turned brown after being left out for too long, then they’ve seen oxidization in action (loss of electrons and nutrients when in contact with oxygen). Fortunately, lemon juice only oxidizes when in contact with heat. This method works with baking soda and milk too. Click here to find out how to write secret messages with your little spy.

Kid-Safe Lava Lamps

A lesson in: Density and intermolecular polarity.

These sound like big words for our little ones, but there’s an easier way to break it down. Water and oil won’t mix because they’re not the same “weight” or substance (just like clay and LEGOs won’t become one). Now add a drop of food coloring (which is heavier than oil) and a fizzy tablet and watch the air bubbles take coloring with them to the top. Head on over to S. L. Smith’s blog to see how it’s done .

Messiness factor: Two sponges.

A Lesson in: Crystallization.

Be careful: The water only has the power to make the sugar crystals “invisible” when it’s piping hot. After the water cools down and evaporates, the sugar turns back into a solid. And with a little help of your sugar-soaked string, the crystals will find a home to grow upon and become rock candy. Learn how to make your smart sweets with these instructions from the Exploratorium .  

S'more Solar Oven

A lesson in: Solar power.

Harness the power of the sun to make your favorite campfire treat! With just a few common household items you can create an  eco-friendly oven  just for melting marshmallows and chocolate, plus you can teach kids about the power of the sun. Click  here  to learn how.

Homemade Slime

A lesson in: Polymers.

Is it a liquid or solid? The answer is both! This DIY slime—made from glue, borax, and water—is also known as a polymer (molecules that can stick close together to be a solid or spread apart and take liquid form). And it’s all thanks to borax, which acts as a binder to prevent the glue from going completely liquid. Check out Explorable’s recipe for mixing the ingredients . Prolong the life of your goo by keeping it in an airtight container in the fridge. And, if you need help with cleanup, check out our guide for how to get slime out of clothes, couches, and hair . 

Make Fizzy Lemonade

Plain old fresh-squeezed lemonade is so last year. Boost the fun quotient and learn a simple science concept simultaneously when you recreate this edible Fizzy Lemonade drink from  Learn With Play at Home . It’s super easy to mix and little sippers report it’s pretty tickly too. A great alternative to the baking soda-vinegar volcano, it shows kids what happens when an acid and base are mixed together. 

Whirlpool in a Bottle

A lesson in: physics, weather science. 

This easy little experiment doesn't take much: just two empty and clear 2-liter bottles, a metal washer, water and duct tape. Food coloring is optional. Fill one bottle with about two-thirds water. Place the washer on the bottle and line up the empty bottle on top of the water-filled one. Wrap the duct tape around the middle securing the two bottles together. Then, turn the bottles upside down. Does the water go straight down or do you see a mini whirlpool (Swirl the top or bottom a bit for a better effect.)? The spinning water is called a vortex, and all tornadoes, hurricanes and typhoons are examples of air vortexes. Since you’re using water, this is an example of a whirlpool. As the water spins faster, it pushes to the outside of the bottle creating a hole in the middle. The air from the bottom of the bottle comes up the middle and the water from the top flows back down through the hole.

Messiness factor : Two sponges.

Salt Crystal Feathers

A lesson in: Evaporation

You’ve probably tried a salt crystal growing kit at some point in your life (5th grade Science Fair perhaps?) but Schooling a Monkey takes the idea to a new level with these Salt Crystal Feathers. This awe-inspiring project is deceptively simple and inexpensive to achieve, and requires just a wee bit of patience to see the results—kids will love checking in on the progress. 

Soda Blasting Experiment

A lesson in: Chemistry, pressure, and release of pressure

This experiment is one you'll definitely want to do outside. Step it up with this Mentos + soda experiment: head to Steve Spangler  for all the need-to-know details on this engaging experiment. 

Messiness factor: Three (very epic) sponges

Melting Rates

A lesson in: Solar science and absorption

Different colors have different heat-absorbing capacities. Black has the greatest heat-absorbing capacity, which results in ice melting quicker than white, which reflects the most light. Learn how to observe and report on which colors affect ice’s melting rates here on Curiodyssey.  Get more sidewalk science ideas here .

Make Elephant Toothpaste

A lesson in:  Chemistry and the exothermic process <<<impress your kids! 

If you’ve ever wondered how elephants keep their tusks clean, we’ve got the answer. They use elephant toothpaste! Find out how to mix your own and figure out the science behind this dynamic exothermic (heat-releasing) reaction from Fun at Home With Kids . Our favorite part? That you get to throw in some sensory playtime after the action’s over.

Messiness factor:  Three sponges. Maybe four. 

Bending Water with a Comb

A lesson in: Electrical currents and static electricity

This  static electricity science experiment couldn't be any easier. In fact, other than a balloon or going down the slide, it might be the easiest way to teach kids about electrical currents. And, you can impress them with your wizarding skills once before you reveal the science behind it. Click here to get the step-by-step. 

Regrow Leftovers

A lesson in : Photosynthesis and plant science.

Insert a little plant science into the mix by re-growing food from scraps. Think onions, potatoes, and lettuce for this one ( psst… green onions are a super easy, fast option). Get the low down on all that recycled goodness at Mrs. Happy Homemaker . Since plants need water and sunlight to grow, exposing scrap roots to that winning combo helps them recharge.

Messiness factor:  Two sponges.

Turning Pennies Green

A lesson in: Chemical reactions.

It happens to the Statue of Liberty and it happens to the change in your pocket! Create your own home lab with just a few household ingredients (this experiment will literally cost you just pennies). It’s also a chemical reaction with very non-toxic ingredients, so it’s safe and fascinating even for young kids. Click over to Buggy and Buddy to get the simple how-to.

Film Canister Rocket

A lesson in: Rocket science.

Like the popular baking soda and vinegar experiments, this film canister rocket literally takes it to the next level by using that creation of gas and energy to jet off into the sky. If your explorer has seen videos of mountain tops getting blown off during a volcanic eruption, this science project is pretty much any space lover’s version. Get the building instructions over at The Science Kiddo .

Disappearing Egg Shell

Can you and the kiddos solve the mysterious case of the disappearing eggshell? Following the simple how-to at Go Science Kids , you’ll learn the step-by-step and talking points about the process along the way. Warning! Although it’s totally non-toxic, toddler-aged kids will be tempted to squeeze the egg at the end so make sure it’s a supervised experiment. Visit Go Science Kids to get cracking!

Fishing for Ice

A lesson in: Freezing/temperature.

Children living in snow-covered cities might witness their neighbors salting the driveway. Well, while that is definitely not for fun, this experiment is. Salt lowers the freezing point of ice so it melts, but it won’t be able to freeze unless it’s cold enough. See how The Science Kiddo made a clever game with this knowledge.

A lesson in: How clouds hold water.

Let your imagineers pretend shaving cream is a cloud that holds colorful raindrops. As they squeeze more and more food coloring, their “cloud” will soon release the excess below—just like how real clouds get too heavy and let the rain loose on a gloomy day. Learn how to re-create this weather experiment here .

Dyed Plants

A lesson in: Capillary action.

Find out how plants “drink” water with some food coloring . Use carnations, roses, or stalks of celery submerged in the colored water and watch the liquid slowly seep through the plant’s “veins” and towards the leaves. Keep an eye out -- you could have a very colorful bouquet just after the first day. Get the rundown by Dad’s Book of Awesome Science Experiments  over  here .

Dancing Oobleck

A lesson in: Sound waves.

The word “oobleck” comes from a Dr. Seuss story where a young boy must rescue his kingdom from a sticky substance. But the neat part of this experiment is how oobleck reacts to vibrations. Put the oobleck over a subwoofer (on top of a cookie sheet!) and watch it dance to different frequencies. Your dancer will see how sound isn’t just about volume! Check out more of this awesome experiment from Tammy of Housing a Forest .

Messiness factor: Five sponges.

Homemade Lightning

A lesson in: Static electricity. (Or weather science.)

Lightning is essentially electrons moving uber fast between the sky and the earth—and with a few simple materials, you can use homemade static electricity (the reason behind your hair sticking up when you rub a balloon or go through a tunnel slide super fast) for DIY lightning. Figure out how to recreate a family-friendly version of this spark by visiting the activity blog Learn Play Imagine .

Make a Bug Vacuum

A Lesson in: Entomology

Scientists capture bugs for study using a mouth-powered vacuum, called an aspirator or a pooter. Kids can make their own version from a mason jar, then use it to gather ants (or other small insects) and observe them in action.

What you'll need: Pint-size mason jar with a two-piece lid Milk or juice carton Hole punch 2 bendy straws Tape Gauze pad

How to:  1. Open the milk carton along the seams and flatten it out. Use the inner lid of the mason jar as a template to trace a circle on the carton. Cut out the circle and punch two holes in the center about an inch apart.

2. Carefully slide the short ends of the bendy straws into the holes. Tape a piece of gauze pad around the end of one straw to prevent any bugs from getting sucked up.

3 Set the lid on the jar and fasten it in place with the ring.

4. To use your pooter, place the tip of the straw without the gauze near a bug. Put your mouth on the straw with the gauze, and gently suck in. The bug should travel up the straw and land unharmed at the bottom of the jar.

Take It Further Capture some ants in your bug vacuum, then use a magnifying glass to observe these remarkable insects up close. Open the jar and feed them a few drops of sugary water or corn syrup, or try giving them some birdseed. Ants live in colonies headed by a queen ant, and they can’t last long on their own. When you are done observing them, release your ants where you found them. (Note: Some ants bite, so be careful handling them.)

Tell Me More Ants were the Earth’s first farmers. For millions of years, certain species have been creating underground gardens where they grow their favorite fungus for food. They tend to their crops, bringing them water and even weeding out other fungi they don’t want.

Excerpted from Mason Jar Science © by Jonathan Adolph, used with permission from Storey Publishing . Available online , $12.69.

Messiness Factor : One sponge. 

A Smell Challenge

A Lesson in: Olfactory senses.

Teach kids the importance of smell with this activity that asks them to use only their noses to identify objects. Can they sniff out the fish oil over the garlic cloves? The lemon juice over the orange oil? Homeschooling blogger Ana has the instructions at Babble Dabble Do .

Is This Soluble?

A Lesson in: Mixtures 

Teaching children chemistry can become a fun, at-home activity as a weekend afternoon project or as part of their remote learning curriculum. One of the best experiments you can do is the mixing activity. With this exercise, children will learn the difference between soluble and insoluble substances. Do not worry! You can do it with ingredients you already have in your kitchen!

Ingredients

• Oil (cooking oil, vegetable oil, olive oil, etc.)
• Food Coloring
• Transparent containers with a lid or transparent cups with a spoon to mix

Before you begin the activity, ask the children what each ingredient is—whether it is a solid, liquid, or gas—and what they think will happen when you begin mixing them. This guarantees a hands-on experiment that will allow the children to feel they are in control.

• Mix the water and the sand. Children will notice there is a separation between both ingredients and that layers have formed, so it is an insoluble reaction.
• Mix the water and the food coloring. Children will see them combine—the water turning into that color—and know it is a soluble reaction.
• Mix the water and the table salt. The salt will disappear in the water, making it another soluble reaction.
• Mix the water and the oil. This time, a clear layer will be formed, showing another insoluble reaction.

After these mixing activities, you can further this experiment by letting the children find other ingredients to mix with water and have them determine if that substance is soluble or insoluble. The main goal is to show them different reactions and layers.

For a clear example of this experiment, check out this video .

Messiness factor: 2 sponges 

Experiment courtesy of Dr. Stephanie Ryan. See more fun about science over at letslearnaboutscience.com

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72 Easy Science Experiments Using Materials You Already Have On Hand

Because science doesn’t have to be complicated.

If there is one thing that is guaranteed to get your students excited, it’s a good science experiment! While some experiments require expensive lab equipment or dangerous chemicals, there are plenty of cool projects you can do with regular household items. We’ve rounded up a big collection of easy science experiments that anybody can try, and kids are going to love them!

Easy Chemistry Science Experiments

Easy physics science experiments, easy biology and environmental science experiments, easy engineering experiments and stem challenges.

1. Taste the Rainbow

Teach your students about diffusion while creating a beautiful and tasty rainbow! Tip: Have extra Skittles on hand so your class can eat a few!

Learn more: Skittles Diffusion

2. Crystallize sweet treats

Crystal science experiments teach kids about supersaturated solutions. This one is easy to do at home, and the results are absolutely delicious!

Learn more: Candy Crystals

3. Make a volcano erupt

This classic experiment demonstrates a chemical reaction between baking soda (sodium bicarbonate) and vinegar (acetic acid), which produces carbon dioxide gas, water, and sodium acetate.

Learn more: Best Volcano Experiments

4. Make elephant toothpaste

This fun project uses yeast and a hydrogen peroxide solution to create overflowing “elephant toothpaste.” Tip: Add an extra fun layer by having kids create toothpaste wrappers for plastic bottles.

5. Blow the biggest bubbles you can

Add a few simple ingredients to dish soap solution to create the largest bubbles you’ve ever seen! Kids learn about surface tension as they engineer these bubble-blowing wands.

Learn more: Giant Soap Bubbles

6. Demonstrate the “magic” leakproof bag

All you need is a zip-top plastic bag, sharp pencils, and water to blow your kids’ minds. Once they’re suitably impressed, teach them how the “trick” works by explaining the chemistry of polymers.

Learn more: Leakproof Bag

7. Use apple slices to learn about oxidation

Have students make predictions about what will happen to apple slices when immersed in different liquids, then put those predictions to the test. Have them record their observations.

Learn more: Apple Oxidation

8. Float a marker man

Their eyes will pop out of their heads when you “levitate” a stick figure right off the table! This experiment works due to the insolubility of dry-erase marker ink in water, combined with the lighter density of the ink.

Learn more: Floating Marker Man

9. Discover density with hot and cold water

There are a lot of easy science experiments you can do with density. This one is extremely simple, involving only hot and cold water and food coloring, but the visuals make it appealing and fun.

Learn more: Layered Water

10. Layer more liquids

This density demo is a little more complicated, but the effects are spectacular. Slowly layer liquids like honey, dish soap, water, and rubbing alcohol in a glass. Kids will be amazed when the liquids float one on top of the other like magic (except it is really science).

Learn more: Layered Liquids

11. Grow a carbon sugar snake

Easy science experiments can still have impressive results! This eye-popping chemical reaction demonstration only requires simple supplies like sugar, baking soda, and sand.

Learn more: Carbon Sugar Snake

12. Mix up some slime

Tell kids you’re going to make slime at home, and watch their eyes light up! There are a variety of ways to make slime, so try a few different recipes to find the one you like best.

13. Make homemade bouncy balls

These homemade bouncy balls are easy to make since all you need is glue, food coloring, borax powder, cornstarch, and warm water. You’ll want to store them inside a container like a plastic egg because they will flatten out over time.

Learn more: Make Your Own Bouncy Balls

14. Create eggshell chalk

Eggshells contain calcium, the same material that makes chalk. Grind them up and mix them with flour, water, and food coloring to make your very own sidewalk chalk.

Learn more: Eggshell Chalk

15. Make naked eggs

This is so cool! Use vinegar to dissolve the calcium carbonate in an eggshell to discover the membrane underneath that holds the egg together. Then, use the “naked” egg for another easy science experiment that demonstrates osmosis .

Learn more: Naked Egg Experiment

16. Turn milk into plastic

This sounds a lot more complicated than it is, but don’t be afraid to give it a try. Use simple kitchen supplies to create plastic polymers from plain old milk. Sculpt them into cool shapes when you’re done!

17. Test pH using cabbage

Teach kids about acids and bases without needing pH test strips! Simply boil some red cabbage and use the resulting water to test various substances—acids turn red and bases turn green.

Learn more: Cabbage pH

18. Clean some old coins

Use common household items to make old oxidized coins clean and shiny again in this simple chemistry experiment. Ask kids to predict (hypothesize) which will work best, then expand the learning by doing some research to explain the results.

Learn more: Cleaning Coins

19. Pull an egg into a bottle

This classic easy science experiment never fails to delight. Use the power of air pressure to suck a hard-boiled egg into a jar, no hands required.

Learn more: Egg in a Bottle

20. Blow up a balloon (without blowing)

Chances are good you probably did easy science experiments like this when you were in school. The baking soda and vinegar balloon experiment demonstrates the reactions between acids and bases when you fill a bottle with vinegar and a balloon with baking soda.

21 Assemble a DIY lava lamp

This 1970s trend is back—as an easy science experiment! This activity combines acid-base reactions with density for a totally groovy result.

22. Explore how sugary drinks affect teeth

The calcium content of eggshells makes them a great stand-in for teeth. Use eggs to explore how soda and juice can stain teeth and wear down the enamel. Expand your learning by trying different toothpaste-and-toothbrush combinations to see how effective they are.

Learn more: Sugar and Teeth Experiment

23. Mummify a hot dog

If your kids are fascinated by the Egyptians, they’ll love learning to mummify a hot dog! No need for canopic jars , just grab some baking soda and get started.

24. Extinguish flames with carbon dioxide

This is a fiery twist on acid-base experiments. Light a candle and talk about what fire needs in order to survive. Then, create an acid-base reaction and “pour” the carbon dioxide to extinguish the flame. The CO2 gas acts like a liquid, suffocating the fire.

25. Send secret messages with invisible ink

Turn your kids into secret agents! Write messages with a paintbrush dipped in lemon juice, then hold the paper over a heat source and watch the invisible become visible as oxidation goes to work.

Learn more: Invisible Ink

26. Create dancing popcorn

This is a fun version of the classic baking soda and vinegar experiment, perfect for the younger crowd. The bubbly mixture causes popcorn to dance around in the water.

27. Shoot a soda geyser sky-high

You’ve always wondered if this really works, so it’s time to find out for yourself! Kids will marvel at the chemical reaction that sends diet soda shooting high in the air when Mentos are added.

Learn more: Soda Explosion

28. Send a teabag flying

Hot air rises, and this experiment can prove it! You’ll want to supervise kids with fire, of course. For more safety, try this one outside.

Learn more: Flying Tea Bags

29. Create magic milk

This fun and easy science experiment demonstrates principles related to surface tension, molecular interactions, and fluid dynamics.

Learn more: Magic Milk Experiment

30. Watch the water rise

Learn about Charles’s Law with this simple experiment. As the candle burns, using up oxygen and heating the air in the glass, the water rises as if by magic.

Learn more: Rising Water

31. Learn about capillary action

Kids will be amazed as they watch the colored water move from glass to glass, and you’ll love the easy and inexpensive setup. Gather some water, paper towels, and food coloring to teach the scientific magic of capillary action.

Learn more: Capillary Action

32. Give a balloon a beard

Equally educational and fun, this experiment will teach kids about static electricity using everyday materials. Kids will undoubtedly get a kick out of creating beards on their balloon person!

Learn more: Static Electricity

33. Find your way with a DIY compass

Here’s an old classic that never fails to impress. Magnetize a needle, float it on the water’s surface, and it will always point north.

Learn more: DIY Compass

34. Crush a can using air pressure

Sure, it’s easy to crush a soda can with your bare hands, but what if you could do it without touching it at all? That’s the power of air pressure!

35. Tell time using the sun

While people use clocks or even phones to tell time today, there was a time when a sundial was the best means to do that. Kids will certainly get a kick out of creating their own sundials using everyday materials like cardboard and pencils.

Learn more: Make Your Own Sundial

36. Launch a balloon rocket

Grab balloons, string, straws, and tape, and launch rockets to learn about the laws of motion.

37. Make sparks with steel wool

All you need is steel wool and a 9-volt battery to perform this science demo that’s bound to make their eyes light up! Kids learn about chain reactions, chemical changes, and more.

Learn more: Steel Wool Electricity

38. Levitate a Ping-Pong ball

Kids will get a kick out of this experiment, which is really all about Bernoulli’s principle. You only need plastic bottles, bendy straws, and Ping-Pong balls to make the science magic happen.

39. Whip up a tornado in a bottle

There are plenty of versions of this classic experiment out there, but we love this one because it sparkles! Kids learn about a vortex and what it takes to create one.

Learn more: Tornado in a Bottle

40. Monitor air pressure with a DIY barometer

This simple but effective DIY science project teaches kids about air pressure and meteorology. They’ll have fun tracking and predicting the weather with their very own barometer.

Learn more: DIY Barometer

41. Peer through an ice magnifying glass

Students will certainly get a thrill out of seeing how an everyday object like a piece of ice can be used as a magnifying glass. Be sure to use purified or distilled water since tap water will have impurities in it that will cause distortion.

Learn more: Ice Magnifying Glass

42. String up some sticky ice

Can you lift an ice cube using just a piece of string? This quick experiment teaches you how. Use a little salt to melt the ice and then refreeze the ice with the string attached.

Learn more: Sticky Ice

43. “Flip” a drawing with water

Light refraction causes some really cool effects, and there are multiple easy science experiments you can do with it. This one uses refraction to “flip” a drawing; you can also try the famous “disappearing penny” trick .

Learn more: Light Refraction With Water

44. Color some flowers

We love how simple this project is to re-create since all you’ll need are some white carnations, food coloring, glasses, and water. The end result is just so beautiful!

45. Use glitter to fight germs

Everyone knows that glitter is just like germs—it gets everywhere and is so hard to get rid of! Use that to your advantage and show kids how soap fights glitter and germs.

Learn more: Glitter Germs

46. Re-create the water cycle in a bag

You can do so many easy science experiments with a simple zip-top bag. Fill one partway with water and set it on a sunny windowsill to see how the water evaporates up and eventually “rains” down.

Learn more: Water Cycle

47. Learn about plant transpiration

Your backyard is a terrific place for easy science experiments. Grab a plastic bag and rubber band to learn how plants get rid of excess water they don’t need, a process known as transpiration.

Learn more: Plant Transpiration

48. Clean up an oil spill

Before conducting this experiment, teach your students about engineers who solve environmental problems like oil spills. Then, have your students use provided materials to clean the oil spill from their oceans.

Learn more: Oil Spill

49. Construct a pair of model lungs

Kids get a better understanding of the respiratory system when they build model lungs using a plastic water bottle and some balloons. You can modify the experiment to demonstrate the effects of smoking too.

Learn more: Model Lungs

50. Experiment with limestone rocks

Kids  love to collect rocks, and there are plenty of easy science experiments you can do with them. In this one, pour vinegar over a rock to see if it bubbles. If it does, you’ve found limestone!

Learn more: Limestone Experiments

51. Turn a bottle into a rain gauge

All you need is a plastic bottle, a ruler, and a permanent marker to make your own rain gauge. Monitor your measurements and see how they stack up against meteorology reports in your area.

Learn more: DIY Rain Gauge

52. Build up towel mountains

This clever demonstration helps kids understand how some landforms are created. Use layers of towels to represent rock layers and boxes for continents. Then pu-u-u-sh and see what happens!

Learn more: Towel Mountains

53. Take a play dough core sample

Learn about the layers of the earth by building them out of Play-Doh, then take a core sample with a straw. ( Love Play-Doh? Get more learning ideas here. )

Learn more: Play Dough Core Sampling

54. Project the stars on your ceiling

Use the video lesson in the link below to learn why stars are only visible at night. Then create a DIY star projector to explore the concept hands-on.

Learn more: DIY Star Projector

55. Make it rain

Use shaving cream and food coloring to simulate clouds and rain. This is an easy science experiment little ones will beg to do over and over.

Learn more: Shaving Cream Rain

56. Blow up your fingerprint

This is such a cool (and easy!) way to look at fingerprint patterns. Inflate a balloon a bit, use some ink to put a fingerprint on it, then blow it up big to see your fingerprint in detail.

57. Snack on a DNA model

Twizzlers, gumdrops, and a few toothpicks are all you need to make this super-fun (and yummy!) DNA model.

Learn more: Edible DNA Model

58. Dissect a flower

Take a nature walk and find a flower or two. Then bring them home and take them apart to discover all the different parts of flowers.

59. Craft smartphone speakers

No Bluetooth speaker? No problem! Put together your own from paper cups and toilet paper tubes.

Learn more: Smartphone Speakers

60. Race a balloon-powered car

Kids will be amazed when they learn they can put together this awesome racer using cardboard and bottle-cap wheels. The balloon-powered “engine” is so much fun too.

Learn more: Balloon-Powered Car

61. Build a Ferris wheel

You’ve probably ridden on a Ferris wheel, but can you build one? Stock up on wood craft sticks and find out! Play around with different designs to see which one works best.

Learn more: Craft Stick Ferris Wheel

62. Design a phone stand

There are lots of ways to craft a DIY phone stand, which makes this a perfect creative-thinking STEM challenge.

63. Conduct an egg drop

Put all their engineering skills to the test with an egg drop! Challenge kids to build a container from stuff they find around the house that will protect an egg from a long fall (this is especially fun to do from upper-story windows).

Learn more: Egg Drop Challenge Ideas

64. Engineer a drinking-straw roller coaster

STEM challenges are always a hit with kids. We love this one, which only requires basic supplies like drinking straws.

Learn more: Straw Roller Coaster

65. Build a solar oven

Explore the power of the sun when you build your own solar ovens and use them to cook some yummy treats. This experiment takes a little more time and effort, but the results are always impressive. The link below has complete instructions.

Learn more: Solar Oven

66. Build a Da Vinci bridge

There are plenty of bridge-building experiments out there, but this one is unique. It’s inspired by Leonardo da Vinci’s 500-year-old self-supporting wooden bridge. Learn how to build it at the link, and expand your learning by exploring more about Da Vinci himself.

Learn more: Da Vinci Bridge

67. Step through an index card

This is one easy science experiment that never fails to astonish. With carefully placed scissor cuts on an index card, you can make a loop large enough to fit a (small) human body through! Kids will be wowed as they learn about surface area.

68. Stand on a pile of paper cups

Combine physics and engineering and challenge kids to create a paper cup structure that can support their weight. This is a cool project for aspiring architects.

Learn more: Paper Cup Stack

69. Test out parachutes

Gather a variety of materials (try tissues, handkerchiefs, plastic bags, etc.) and see which ones make the best parachutes. You can also find out how they’re affected by windy days or find out which ones work in the rain.

Learn more: Parachute Drop

70. Recycle newspapers into an engineering challenge

It’s amazing how a stack of newspapers can spark such creative engineering. Challenge kids to build a tower, support a book, or even build a chair using only newspaper and tape!

Learn more: Newspaper STEM Challenge

71. Use rubber bands to sound out acoustics

Explore the ways that sound waves are affected by what’s around them using a simple rubber band “guitar.” (Kids absolutely love playing with these!)

Learn more: Rubber Band Guitar

72. Assemble a better umbrella

Challenge students to engineer the best possible umbrella from various household supplies. Encourage them to plan, draw blueprints, and test their creations using the scientific method.

Learn more: Umbrella STEM Challenge

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32 physics experiments that changed the world

From the discovery of gravity to the first mission to defend Earth from an asteroid, here are the most important physics experiments that changed the world.

Physics experiments have changed the world irrevocably, altering our reality and enabling us to take gigantic leaps in technology. From ancient times to now, here's a look at some of the greatest physics experiments of all time.

Conservation of energy

Energy conservation — the idea that energy cannot be created or destroyed, only transformed — is one of the most important laws of physics. James Prescott Joule demonstrated this rule, the first law of thermodynamics , when he filled a large container with water and fixed a paddle wheel inside it. The wheel was held in place by an axle with a string around it and then looped over a pulley and attached to a weight, which, when dropped, caused the wheel to spin. By sloshing the water with the wheel, Joule demonstrated that the heat energy gained by the water from the wheel's movement was equal to the potential energy lost by dropping the weight.

Measurement of the electron's charge

As the fundamental carriers of electric charge, electrons carry the smallest amount of electricity possible. But the particles are truly tiny, with a mass 1,838 times smaller than the already-minuscule proton.

So how could you measure the charge on something so small? Physicist Robert Millikan's answer was to drop electrically charged oil drops through the plates of a capacitor and adjust the voltage of the capacitor until the electric field it emitted produced a force on some of the drops that balanced out gravity — thus suspending them in the air. Repeating the experiment for different voltages revealed that, no matter the size of the drops, the total charge it carried was a multiple of a base number. Millikan had found the fundamental charge of the electron.

 "Gold foil experiment" revealing the structure of the atom

Once thought to be indivisible, the atom was slowly divided and split by a series of experiments during the late 19th and early 20th centuries. These included J.J. Thomson's 1897 discovery of the electron and James Chadwick's 1932 identification of the neutron. But perhaps the most famous of these experiments was Hans Geiger and Ernest Marsden's " gold foil experiment ." Under the direction of Ernest Rutherford, the students fired positively charged alpha particles at a thin sheet of gold foil. To their surprise, the particles passed through, revealing that atoms consisted of a positively charged nucleus separated by a significant empty space by their orbiting electrons.

Nuclear chain reaction

By the mid-20th century, scientists were aware of the basic structure of the atom and that, according to Einstein, matter and energy were different forms of the same thing. This set the stage for the wartime work of Enrico Fermi, who in 1942 demonstrated that atoms could be split to release enormous quantities of energy.

While working at the University of Chicago with an experimental setup he called an "atomic pile," Fermi demonstrated the first-ever controlled nuclear fission reaction. Fermi fired neutrons at the unstable isotope uranium-235, causing it to split and release more neutrons in a growing chain reaction. The experiment paved the way for the development of nuclear reactors and was used by J. Robert Oppenheimer and the Manhattan Project to build the first atomic bombs.

Wave-particle duality

One of the most famous experiments in physics is also one that illustrates, with disturbing simplicity, the bizarreness of the quantum world. The experiment consisted of two slits, through which electrons would travel to create an interference pattern on a screen, like waves. Scientists were stunned when they placed a detector near the screen and found that its presence caused the electrons to switch their behavior to act instead as particles.

First performed by Thomas Young to demonstrate the wave nature of light, the experiment was later used by physicists in the 20th century to show that all particles, including photons , were both waves and particles at the same time — and they acted more like particles when they were being measured directly.

Splitting of white light into colors

White light is a mixture of all the colors of the rainbow, but before 1672, the composite nature of light was completely unknown. Isaac Newton determined this by using a prism that bent light of different wavelengths, or colors, by different amounts, decomposing white light into its composite colors. The result was one of the most famous experiments in scientific history and a discovery that, alongside other contributions by Newton, gave birth to the modern field of optics.

Discovery of gravity

In perhaps the most widely repeated story in all of science, Newton is said to have chanced upon the theory of gravity while contemplating under the shade of an apple tree. According to the legend, when an apple fell and struck him on the head, he supposedly yelled "Eureka!" as he realized that the same force that brought the apple tumbling to Earth also kept the moon in orbit around our planet and Earth circling the sun. That force, of course, would become known as gravity .

The story is slightly embellished, however. According to Newton's own account, the apple did not strike him on the head, and there's no record of what he said or if he said anything, at the moment of discovery. Nonetheless, the realization led Newton to develop his theory of gravity in 1687, which was updated by Einstein's theory of general relativity 228 years later.

Blackbody radiation

By the turn of the 20th century, many physicists — having advanced theories that explained gravity, mechanics, thermodynamics and the behavior of electromagnetic fields — were confident that they had conquered the vast majority of their field. But one troubling source of doubt remained: Theories predicted the existence of a "blackbody" — an object capable of absorbing and then remitting all incident radiation. The problem was that physicists couldn't find it.

In fact, data from experiments conducted with close approximations of black bodies — a box with a single hole whose inside walls are black — revealed that significantly less energy was emitted from blackbodies than classical theories led scientists to believe, especially at shorter wavelengths. The contradiction between experiment and theory became known as the "ultraviolet catastrophe."

The discovery prompted Max Planck to propose that the energy emitted by blackbodies wasn't continuous but rather split into discrete integer chunks called quanta. His radical proposal catalyzed the development of quantum mechanics , whose bizarre rules are completely unintuitive to observers living in the macroscopic world.

Einstein and the eclipse

Following its publication in 1915, Einstein's groundbreaking theory of general relativity briefly remained just that — a theory. Then, in 1919, astronomer Sir Arthur Eddington devised and completed stunning proof using that year's total solar eclipse .

Key to Einstein's theory was the notion that space — and, therefore, the path that light would follow through it — was warped by powerful gravitational forces. So, as the moon's shadow passed in front of the sun, Eddington recorded the position of nearby stars from his vantage point on the island of Principe in the Gulf of Guinea. By comparing these positions to those he had recorded at night without the sun in the sky, Eddington observed that they had been shifted slightly by the sun's gravity, completing his stunning proof of Einstein's theory.

Higgs boson

In 1964, Peter Higgs suggested that matter gets its mass from a field that permeates all of space, imparting particles with mass through their interactions with a particle known as the Higgs boson .

To search for the boson, thousands of particle physicists planned, constructed and fired up the Large Hadron Collider . In 2012, after trillions upon trillions of collisions in which two protons are smashed together at near light speed, the physicists finally spotted the telltale signature of the boson.

Weighing the world

Although he's perhaps best known for his discovery of hydrogen, 18th-century physicist Henry Cavendish's most ingenious experiment accurately estimated the weight of our entire planet. Using a special piece of equipment known as a torsion balance (two rods with one smaller and one larger pair of lead balls attached to the end), Cavendish measured the minuscule force of gravitational attraction between the masses. Then, by measuring the weight of one of the small balls, he measured the gravitational force between it and Earth, giving him an easy formula for calculating our planet's density and — therefore, its weight — that remains accurate to this day.

Conservation of mass

Much like energy, matter in our universe is finite and cannot be created or destroyed, only rearranged. In 1789, to arrive at this startling conclusion, French chemist Antoine Lavoisier placed a burning candle inside a sealed glass jar. After the candle had burned and melted into a puddle of wax, Lavoisier weighed the jar and its contents, finding that it had not changed

Leaning Tower of Pisa experiment

Greek philosopher Aristotle believed that objects fall at different rates because the force acting upon them was stronger for heavier objects — a claim that went unchallenged for more than a millennium.

Then came the Italian polymath Galileo Galilei, who corrected Aristotle's false claim by showing that two objects with different masses fall at exactly the same rate. Some claim Galileo's famous experiment was conducted by dropping two spheres from the Leaning Tower of Pisa, but others say this part of the story is apocryphal. Nonetheless, the experiment was perhaps most famously demonstrated by Apollo 15 astronaut David Scott, who, while dropping a feather and a hammer on the moon, showed that without air, the two objects fell at the same speed.

Detection of gravitational waves

If gravity warps space-time as Einstein predicted, then the collision of two extremely dense objects, such as neutron stars or black holes , should also create detectable shock waves in space that could reveal physics unseen by light. The problem is that these gravitational waves are tiny, often the size of a few thousandths of a proton or neutron, so detecting them requires an extremely sensitive experiment.

Enter LIGO, the Laser Interferometer Gravitational-Wave Observatory. The L-shaped detector has two 2.5-mile-long (4 km) arms containing two identical laser beams. When a gravitational wave laps at our cosmic shores, the laser in one arm is compressed and the other expands, alerting scientists to the wave's presence. In 2015, LIGO achieved its task, making the first-ever direct detection of gravitational waves and opening up an entirely new window to the cosmos.

Destruction of heliocentrism

The idea that Earth orbits the sun goes back to the fifth century B.C. to Greek philosophers Hicetas and Philolaus. Nonetheless, Claudius Ptolemy's belief that Earth was the center of the universe later took root and dominated scientific thought for more than a millennium.

Then came Nicolaus Copernicus, who proposed that Earth did, in fact, revolve around the sun and not the other way around. Concrete evidence for this was later offered by Galileo, who in 1610 peered through his telescope to observe the planet Venus moving through distinct phases — proof that it, too, orbited the sun. Galileo's discovery did not win him any friends with the Catholic Church, which tried him for heresy for his unorthodox proposal.

Foucault's pendulum

First used by French physicist Jean Bernard Léon Foucault in 1851, the famous pendulum consisted of a brass bob containing sand and suspended by a cable from the ceiling. As it swung back and forth, the angle of the line traced out by the sand changed subtly over time — clear evidence that some unknown rotation was causing it to shift. This rotation was the spinning of Earth on its axis.

Discovery of the electron

In the 19th century, physicists found that by creating a vacuum inside a glass tube and sending electricity through it, they could make the tube give off a fluorescent glow. But exactly what caused this effect, called a cathode ray, was unclear.

Then, in 1897, physicist J.J. Thomson discovered that by applying a magnetic field to the rays inside the tube, he could control the direction in which they traveled. This revelation showed Thomson that the charge within the tube came from tiny particles 1,000 times smaller than hydrogen atoms. The tiny electron had finally been found.

Deflection of an asteroid

In 2022, NASA scientists hit an astronomical "bull's-eye" by intentionally steering the 1,210-pound (550 kilograms), $314 million Double Asteroid Redirection Test (DART) spacecraft into the asteroid Dimorphos just 56 feet (17 meters) from its center. The test was designed to see if a small spacecraft propelled along a planned trajectory could, if given enough lead time, redirect an asteroid from a potentially catastrophic impact with Earth.

DART was a smashing success . The probe's original goal was to change the orbit of Dimorphos around its larger partner — the 2,560-foot-wide (780 m) asteroid Didymos — by at least 73 seconds, but the spacecraft actually altered Dimorphos' orbit by a stunning 32 minutes. NASA hailed the collision as a watershed moment for planetary defense, marking the first time that humans proved capable of diverting Armageddon, and without any assistance from Bruce Willis.

Faraday induction

In 1831, Michael Faraday, the self-taught son of a blacksmith born in rural south England, proposed the law of electromagnetic induction. The law was the result of three experiments by Faraday, the most notable of which involved the movement of a magnet inside a coil made by wrapping a wire around a paper cylinder. As the magnet moved inside the cylinder, it induced an electric current through the coil — proving that electric and magnetic fields were inextricably linked and paving the way for electric generators and devices.

Measurement of the speed of light

Light is the fastest thing in our universe, which makes measuring its speed a unique challenge. In 1676, Danish astronomer Ole Roemer chanced upon the first estimate for light's propagation while studying Io, Jupiter's innermost moon. By timing the eclipses of Io by Jupiter, Roemer was hoping to find the moon's orbital period.

What he noticed instead was that, as Earth's orbit moved closer to Jupiter, the time intervals between successive eclipses became shorter. Roemer's crucial insight was that this was due to a finite speed of light, which he roughly calculated based on Earth's orbit. Other methods later refined the measurement of light's speed, eventually arriving at its current value of 2.98 × 10^8 meters per second (about 186,282 miles per second).

Disproof of the "luminiferous ether"

Most waves, such as sound waves and water waves, require a medium to travel through. In the 19th century, physicists thought the same rule applied to light, too, with electromagnetic waves traveling through a ubiquitous medium dubbed the "luminiferous ether."

Albert Michelson and Edward W. Morley set out to prove this conjecture with a remarkably ingenious hypothesis: As the sun moves through the ether, it should displace some of the strange substance, meaning light should travel detectably faster when it moves with the ether wind than against it. They set up an interferometer experiment that used mirrors to split light beams along two opposing directions before bouncing them back with distant mirrors. If the light beams returned at different times, then the ether was real.

But the light beams inside their interferometer did not vary. Michelson and Morley concluded that their experiment had failed and moved on to other projects. But the result — which had conclusively disproved the ether theory — was later used by Einstein in his theory of special relativity to correctly state that light's speed through a fixed medium does not change, even if its source is moving.

Discovery of radioactivity

In 1897, while working in a converted shed with her husband Pierre, Marie Curie began to investigate the source of a strange new type of radiation emitted from the elements thorium and uranium. Marie Curie discovered that the radiation these elements emitted did not depend on any other factors, such as their temperature or molecular structure, but changed purely based on their quantities. While grinding up an even more radioactive substance known as pitchblende, she also discovered that it consisted of two elements that she dubbed radium and polonium.

Curie's work revealed the nature of radioactivity, a truly random property of atoms that comes from their internal structure. Curie won the Nobel Prize (twice) for her discoveries — making her the first woman to do so — and later trained doctors to use X-rays to image broken bones and bullet wounds. She died of aplastic pernicious anemia, a disease caused by radiation exposure, in 1934.

Expansion of the universe

While using the 100-inch Hooker telescope in California to study the light glimmering from distant galaxies in 1929, Edwin Hubble made a surprising observation: The light from the distant galaxies appeared to be shifted toward the red end of the spectrum — an indication that they were receding from Earth and each other. The farther away a galaxy was, the faster it was moving away.

Hubble's observation became a crucial piece of evidence for the Big Bang theory of our universe. Yet precise measurements for galaxies' recession, known as the Hubble constant, still confound scientists to this day .

Put simply, the universe is indeed expanding, but depending on where cosmologists look, it's doing so at different rates. In the past, the two best experiments to measure the expansion rate were the European Space Agency 's Planck satellite and the Hubble Space Telescope . The two observatories, each of which used a different method to measure the expansion rate, arrived at different results. These conflicting measurements have led to what some call a "cosmology crisis" that could reveal new physics or even replace the standard model of cosmology.

Ignition of nuclear fusion

In 2022, scientists at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory in California used the world's most powerful laser to achieve something physicists have been dreaming about for nearly a century: the ignition of a pellet of fuel by nuclear fusion .

The demonstration marked the first time that the energy going out of the plasma in the nuclear reactor's fiery core exceeded the energy beamed in by the laser, and has been a rallying call for fusion scientists that the distant goal of near-limitless and clean power is, in fact, achievable.

However, scientists have cautioned that the energy from the plasma exceeds only that from the lasers, and not from the energy from the whole reactor. Additionally, the laser-confinement method used by the NIF reactor, built to test thermonuclear explosions for bomb development, will be difficult to scale up.

Measurement of Earth's circumference

By roughly 500 B.C., most ancient Greeks believed the world was round — citing evidence provided by Aristotle and guided by a suggestion from Pythagoras, who believed a sphere was the most aesthetically pleasing shape for our planet.

Then, around 245 B.C., Eratosthenes of Cyrene thought of a way to make the measurement directly. Eratosthenes hired a team of bematists (professional surveyors who measured distances by walking in equal-length steps called stadia) to walk from Syene to Alexandria. They found that the distance between the two cities was roughly 5,000 stadia.

Eratosthenes then visited a well in Syene that had been reported to have an interesting property: At noon on the summer solstice each year, the sun illuminated the well's bottom without casting any shadows. Eratosthenes went to Alexandria during the solstice, stuck a pole in the ground and measured the shadow from it to be about one-fiftieth of a complete circle. Pairing this with his measurement of the distance between the two cities, he determined that Earth's circumference was about 250,000 stadia, or 24,497 miles (39,424 km). Earth is now known to measure 24,901 miles (40,074 km) around the equator, making the ancient Greeks' measurements remarkably accurate.

Discovery of black holes

The acceptance of Einstein's theory of general relativity led to some startling predictions about our universe and the nature of reality. In 1915, Karl Schwarzschild's solutions to Einstein's field equations predicted that it was possible for mass to be compressed into such a small radius that it would collapse into a gravitational singularity from which not even light could escape — a black hole.

Schwarzschild's solution remained speculation until 1971, when Paul Murdin and Louise Webster used NASA's Uhuru X-ray Explorer Satellite to identify a bright X-ray source in the constellation Cygnus that they correctly contended was a black hole.

More conclusive evidence came in 2015, when the LIGO experiment detected gravitational waves from two of the colliding cosmic monsters. Then, in 2019, the Event Horizon Telescope captured the first image of the accretion disk of superheated matter surrounding the supermassive black hole at the center of the galaxy M87.

Discovery of X-rays

While testing whether the radiation produced by cathode rays could escape through glass in 1895, German physicist Wilhelm Conrad Röntgen saw that the radiation could not only do so, but it could also zip through very thick objects, leaving a shadow on a lead screen placed behind them. He quickly realized the medical potential of these rays — later known as X-rays — for imaging skeletons and organs. His observations gave birth to the field of radiology, enabling doctors to safely and noninvasively scan for tumors, broken bones and organ failure.

The Bell test

In 1964, physicist John Stewart Bell proposed a test to prove that quantum entanglement — the weird instantaneous connection between two far-apart particles that Einstein objected to as "spooky action at a distance" — was required by quantum theory.

The test has taken many experimental forms since Bell first proposed it, but the findings remain the same: Despite what our intuition tells us, what happens in one part of the universe can instantaneously affect what happens in another, provided the objects in each region are entangled.

Detection of the quark

In 1968, experiments at the Stanford Linear Accelerator Center found that electrons and their lepton cousins, muons, were scattering from protons in a distinct way that could only be explained by the protons being composed of smaller components. These findings matched predictions by physicist Murray Gell-Mann, who dubbed them "quarks" after a line in James Joyce's "Finnegans Wake."

Archimedes' naked leap from his bathtub

First recorded in the first century B.C. by Roman architect Vitruvius, Archimedes' discovery of buoyancy is one of the most famous stories in science. The prompting for Archimedes' finding came from King Hieron of Syracuse, who suspected that a pure-gold crown a blacksmith made for him actually contained silver. To get an answer, Hieron enlisted Archimedes' help.

The problem stumped Archimedes, but not long after, as the story goes, he filled up a bathtub with water and noticed that the water spilled out as he got in. This caused him to realize that the water displaced by his body was equal to his weight — and because gold weighed more than silver, he had found a method for judging the authenticity of the crown. "Eureka!" ("I've got it!") Archimedes is said to have cried, leaping from his bathtub to announce his discovery to the king.

Deepest and most detailed photo of the universe

In 2022, the James Webb Space Telescope unveiled the deepest and most detailed picture of the universe ever taken . Called "Webb's First Deep Field," the image captures light as it appeared when our universe was just a few hundred million years old, right when galaxies began to form and light from the first stars started flickering.

The image contains an overwhelmingly dense collection of galaxies, the light from which, on its way to us, was warped by the gravitational pull of a galaxy cluster. This process, known as gravitational lensing, brings the fainter light into focus. Despite the dizzying number of galaxies in view, the image represents just a tiny sliver of sky — the speck of sky blocked out by a grain of sand held on the tip of a finger at arm's length.

OSIRIS-REx asteroid-sampling mission

In 2023, NASA's OSIRIS-REx spacecraft came hurtling back through Earth's atmosphere after a years-long journey to Bennu, a " potentially hazardous asteroid " with a 1-in-2,700 chance of smashing cataclysmically into Earth — the highest odds of any identified space object.

The goal of the mission was to see whether the building blocks for life on Earth came from outer space. OSIRIS-REx circled the asteroid for 22 months to search for a landing spot, touching down to collect a 2-ounce (60 grams) sample from Bennu's surface that could contain the extraterrestrial precursors to life on our planet. Scientists have already found many surprising details that have the potential to rewrite the history of our solar system .

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Ben Turner is a U.K. based staff writer at Live Science. He covers physics and astronomy, among other topics like tech and climate change. He graduated from University College London with a degree in particle physics before training as a journalist. When he's not writing, Ben enjoys reading literature, playing the guitar and embarrassing himself with chess.

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by Chris Woodford . Last updated: January 6, 2023.

Photo: There are always new theories to test and experiments to try. Even when we've completely nailed how Earth works, there's still the rest of the Universe to explore! Fourier telescope experiment photo by courtesy of NASA .

1: Galileo demonstrates that objects fall at the same speed (1589)

Photo: Galileo proved that different things fall at the same speed.

2: Isaac Newton splits white light into colors (1672)

Artwork: A glass prism splits white light into a spectrum. Nature recreates Newton's famous experiment whenever you see a rainbow!

3: Henry Cavendish weighs the world (1798)

Artwork: Henry Cavendish's experiment seen from above. 1) Two small balls, connected by a stick, are suspended by a thread so they're free to rotate. 2) The balls are attracted by two much larger (more massive) balls, fixed in place. 3) A light beam shines from the side at a mirror (green), mounted so it moves with the small balls. The beam is reflected back onto a measuring scale. 4) As the two sets of balls attract, the mirror pivots, shifting the reflected beam along the scale, so allowing the movement to be measured.

4: Thomas Young proves light is a wave... or does he? (1803)

Artwork: Thomas Young's famous double-slit experiment proved that light behaved like a wave—at least, some of the time. Left: A laser (1) produces coherent (regular, in-step) light (2) that passes through a pair of slits (3) onto a screen (4). If Newton were completely correct, we'd expect to see a single bright area on the screen and darkness either side. What we actually see is shown on the right. Light appears to ripple out in waves from the two slits (5), producing a distinctive interference pattern of light and dark areas (6).

5: James Prescott Joule demonstrates the conservation of energy (1840)

Artwork: The "Mechanical Equivalent of Heat"—James Prescott Joule's famous experiment proving the law now known as the conservation of energy.

6: Hippolyte Fizeau measures the speed of light (1851)

Artwork: How Fizeau measured the speed of light.

7: Robert Millikan measures the charge on the electron (1909)

Artwork: How Millikan measured the charge on the electron. 1) Oil drops (yellow) are squirted into the experimental apparatus, which has a large positive plate (blue) on top and a large negative plate (red) beneath. 2) X rays (green) are fired in. 3) The X rays give the oil drops a negative electrical charge. 4) The negatively charged drops can be made to "float" in between the two plates so their weight (red) is exactly balanced by the upward electrical pull of the positive plate (blue). When these two forces are equal, we can easily calculate the charge on the drops, which is always a whole number multiple of the basic charge on the electron.

8: Ernest Rutherford (and associates) split the atom (1897–1932)

Artwork: Transmutation: When Rutherford fired alpha particles (helium nuclei) at nitrogen, he produced oxygen. As he later wrote: "We must conclude that the nitrogen atom is disintegrated under the intense forces developed in a close collision with a swift alpha particle, and that the hydrogen atom which is liberated formed a constituent part of the nitrogen nucleus." In other words, he had split one atom apart to make another one.

Artwork: In Rutherford's gold-foil experiment (also known as the Geiger-Marsden experiment), atoms in a sheet of gold foil (1) allow positively charged alpha particles to pass through them (2) as long as the particles are traveling clear of the nucleus. Any particles fired at the nucleus are deflected by its positive charge (3). Fired at exactly the right angle, they will bounce right back! While this experiment is not splitting any atoms, as such, it was a key part of the decades-long effort to understand what atoms are made of—and in that sense, it did help physicists to "split" (venture inside) the atom.

9: Enrico Fermi demonstrates the nuclear chain reaction (1942)

Artwork: The nuclear chain reaction that turns uranium-235 into uranium-236 with a huge release of energy.

10: Rosalind Franklin photographs DNA with X rays (1953)

Artwork: The double-helix structure of DNA. Photographed with X rays, these intertwined curves appear as an X shape. Studying the X pattern in one of Franklin's photos was an important clue that tipped off Crick and Watson about the double helix.

If you liked this article...

Don't want to read our articles try listening instead, find out more, on this website.

• Six Easy Pieces by Richard Feynman. Basic Books, 2011. This book isn't half as "easy" as the title suggests, but it does contain interesting introductions to some of the topics covered here, including the conservation of energy, the double-slit experiment, and quantum theory.
• The Oxford Handbook of the History of Physics by Jed Z. Buchwald and Robert Fox (eds). Oxford University Press, 2013/2017. A collection of twenty nine scholarly essays charting the history of physics from Galileo's gravity to the age of silicon chips.
• Great Experiments in Physics: Firsthand Accounts from Galileo to Einstein Edited by Maurice Shamos. Dover, 1959/1987. This is one of my favorite science books, ever. It's a great compilation of some classic physics experiments (including four of those listed here—the experiments by Henry Cavendish, Thomas Young, James Joule, and Robert Millikan) written by the experimenters themselves. A rare opportunity to read firsthand accounts of first-rate science!

Text copyright © Chris Woodford 2012, 2023. All rights reserved. Full copyright notice and terms of use .

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One of the World’s Oldest Science Experiments Comes Up From the Dirt

Every 20 years under the cover of darkness, scientists dig up seeds that were stashed 142 years ago beneath a college campus.

By Cara Giaimo

On Thursday morning, several hours before sunrise, Marjorie Weber arrived at a rendezvous spot on the campus of Michigan State University. Three of the school’s other plant scientists were already there, waiting in dribbling snow. As they stood around blowing on their hands, the fifth member of their crew, Frank Telewski, “emerged from the darkness with a shovel slung over his shoulder,” Dr. Weber said.

With everyone else crowded around, Dr. Telewski, the group’s leader, pulled out a copy of a map, drawn like an architectural blueprint. It would guide them to a botanist’s version of buried treasure: a bottle filled with sand and a bunch of really old seeds.

Dr. Weber and her colleagues are the latest custodians of the Beal seed viability experiment: a multicentury attempt to figure out how long seeds can lie dormant in the soil without losing their ability to germinate. Every 20 years, the experiment’s caretakers creep out to a secret location under cover of night, dig up a bottle, scatter its seeds over a tray of sterile soil and see which ones grow.

It’s one of the world’s longest-running experiments, having already gone on for 142 years. And the botanists in East Lansing hope that it will last for at least another 80.

What started out as a straightforward attempt to measure seed persistence has grown into a more interesting experiment as the decades pass. With technology improving and knowledge increasing, the keepers of the cache can do more than just count each bottle’s successful sprouts. They can look inside seeds to see how they tick, begin to determine what accounts for longevity — and even, in some cases, get species that seemed done for to spring up again. Lessons from their work could help with everything from restoring damaged ecosystems to storing crop seeds for the long-term.

But first, they had to find where to dig.

A long row to hoe

The bottle the team was looking for contains over a thousand seeds: 50 each of 21 different species, from black mustard to white clover to redroot amaranth.

In 1879, William James Beal, a botanist at Michigan State, filled 20 such bottles and buried them in a row somewhere on campus. He figured he — and later, his successors — could dig one up every five years and plant the preserved seeds inside.

When seeds are shed by their parents, they don’t always grow right away. Under any given patch of land, there’s a constellation of sleeping seeds, “biding their time,” Dr. Weber said. Often, they lie dormant — for a season, a few years or even longer — until they get the right set of cues to sprout.

This plant reserve is known as the seed bank. By experimentally recreating it, Dr. Beal hoped to better understand how long plants could last in the soil, and what triggers them to grow. He was likely trying to help local farmers — frustrated by endless weeding, and wondering how long it would take “before they might have some hope of seeing a decline in the seed bank, and their workload going down,” Dr. Telewski said.

For the first few rounds of the experiment, a number of species flourished, with seeds growing readily after 10, 15 or 20 years. As the decades passed, most dropped off one by one. Only one reliable sprouter is left: Verbascum blattaria, a splay-leaved, yellow-flowered herb. Nearly half the Verbascum seeds from 2000’s bottle bloomed, even though they’d been in stasis underground for over a century.

Today, farmers don’t really need the kind of help with weeds that motivated Beal to bury his bottles. But plant scientists have become invested in the question of which seeds last and how for other reasons.

The soil seed banks underlying different habitats are “great unknowns” in restoration ecology, as experts try to promote native species while fending off invasive ones, said Lars Brudvig, an assistant professor at Michigan State and another member of the Beal seed experiment team. In some cases, seeds of endangered or long-lost plants may even be hiding out in the soil.

Other researchers working on questions of longevity and germination might save seeds in climate-controlled environments, or study very old ones that they happen to find. But Dr. Beal’s is the longest-running seed experiment to mix natural conditions with carefully recorded data, said Carol Baskin, a professor of plant and soil sciences at the University of Kentucky who has used its results in her work.

“I think Professor Beal’s got the top experiment here,” Dr. Baskin said. “I wish he’d have buried more bottles.”

Seed stewards

Armed with shovels, gloves and headlamps, the team followed their map to the dig site. The vibe was “very piratey,” Dr. Weber said. Dr. Telewski set to digging a neat, squared-off hole.

But as they carved deeper and wider, there were no bottles to be found. “The birds were starting to chirp,” Dr. Weber said, and the sun threatened to blow their cover. “Morale was low.”

When Dr. Beal first buried the seed bottles, he planned to have one dug up every 5 years, and for the experiment to last a century. But as time passed, those in charge extended the span between digs to 10 years, then 20. Two have been slightly delayed: 1919’s was moved to the spring of 1920 — which Dr. Telewski suspects may have been related to the 1918 flu; and 2020’s was moved to this year, because of Covid-19-related campus shutdowns.

To avoid losing the thread across these decades, a sort of ministry of seed-keepers has developed at Michigan State, with each generation of botanists passing the torch to younger colleagues.

Dr. Telewski — a professor of plant biology at the university, and the seventh person in charge of the experiment — dug up his first seed bottle in 2000 with his predecessor, Jan Zeevaart, who died in 2009. A couple of years ago, mulling his own mortality, he gave a copy of the map to David Lowry, an associate professor of plant biology who had expressed interest in joining up.

Just a couple of months later, Dr. Telewski suffered a stroke. While he has since recovered, “it just showed me how delicate it is to hand these things off while keeping them secret,” Dr. Lowry said. Soon after, Dr. Telewski invited Dr. Weber, who is an assistant professor at the university, and Dr. Brudvig to get involved as well.

Over the years, what were purely practical decisions by Dr. Beal have developed a patina of mystique. Dr. Beal excavated each new bottle under cover of darkness not to be dramatic, but simply to protect the other bottled seeds from sunlight, which might cause them to germinate before their time, Dr. Telewski said. (The team uses green bulbs in their headlamps for the same reason.)

The paper map was drawn after the landmarks that originally indicated the bottles’ location were moved. And the stealth is newly necessary because the older the experiment gets, the more interest it draws, he said.

These “cloaked, secretive” elements are now part of the experiment’s charm, Dr. Weber said. But it’s camaraderie and a desire to see the experiment through that keeps things going. The night before the dig, Dr. Telewski sent a pump-up email to the group. It included his own five-verse reimagining of Simon & Garfunkel’s “The Sound of Silence.” A sample lyric: “Hello bottles my old friends / I’ve come to dig you up again.”

Hearing about the experiment before he came to Michigan State, “I could imagine druids going out in the night and digging this thing up,” said Dr. Lowry. “Now that I know who’s involved, it’s like — ‘Hey, it’s just Frank.’”

Old seeds; new tricks

A little past 6 a.m., with daylight creeping up, Dr. Lowry realized they’d been reading the map wrong. A recalibration set them digging about two feet west.

After some false alarms — tree roots, a rock — Dr. Weber, now digging with her hands, hit something smooth. Slowly, she eased the bottle out of the ground as her fellow initiates cheered. “It kind of felt like delivering a baby, or finding a really important treasure,” she said. “There was a huge sense of relief.”

This year, for the first time, the dug-up seeds didn’t go straight to the growth chamber. Instead, another member of the team, Margaret Fleming, a postdoctoral researcher, brought them to a cold room, where she removed some seeds of Setaria glauca — a species of millet, which hasn’t sprouted in the experiment since 1914 — for genetic analysis.

Planting a seed is like asking it a yes or no question: The seed either sprouts or it doesn’t. But often a seed that doesn’t grow isn’t fully dead. Examining its DNA and RNA lets scientists interrogate it much further — they can find out whether its machinery has degraded or persisted, how damaged the genetic material is and what processes may still be possible even if germination isn’t, Dr. Fleming said.

Bringing in a new generation of stewards is an opportunity to rethink the experiment’s possibilities. When these seeds were buried, “we didn’t even know what DNA was,” Dr. Telewski said. Multiple generations in, “very fundamental questions that are going to really help us understand seed dormancy and seed viability can now begin to be addressed.”

The stakes of these questions are also changing. Recent decades have seen a growing number of seed storage projects, including Indigenous food sovereignty efforts and doomsday-prevention crop seed vaults . A better understanding of what allows specific seeds to stay functional while dormant, as well as what causes them to sprout, could help with this work.

After the rest of the seeds are sown and watered, the team will keep watch, expecting the 142-year-old Verbascum seeds to put forth tender green shoots.

Then they’ll try some more tricks based on discoveries from the field of plant ecology. For starters, they’ll put the whole bed of soil through a cold treatment to simulate a second winter — a move that, in the 2000 batch, yielded a single seedling of a mallow species, Malva pusilla.

They’ll also try something new: exposing the seeds to smoke. This may trigger germination in some plants which are known to thrive after wildfires, such as Erechtites hieraciifolius, or fireweed, which has never once sprouted during the experiment.

The team is eager for the results of these growth tests, which should come in the next couple of weeks.

But they also are looking forward to “19 years from now,” Dr. Brudvig said, “when we’re going to be seeking out the young colleagues in the department and saying ‘Psst, hey — can I show you a map?’”

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Hearing Aids in Your Pocket:  With the help of new software authorized by the F.D.A., Apple is preparing to turn its AirPods Pro 2 into easy-to-use aids  for people with mild to moderate hearing loss.

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37 Cool Science Experiments for Kids to Do at Home

General Education

Are you looking for cool science experiments for kids at home or for class? We've got you covered! We've compiled a list of 37 of the best science experiments for kids that cover areas of science ranging from outer space to dinosaurs to chemical reactions. By doing these easy science experiments, kids will make their own blubber and see how polar bears stay warm, make a rain cloud in a jar to observe how weather changes, create a potato battery that'll really power a lightbulb, and more.

Below are 37 of the best science projects for kids to try. For each one we include a description of the experiment, which area(s) of science it teaches kids about, how difficult it is (easy/medium/hard), how messy it is (low/medium/high), and the materials you need to do the project. Note that experiments labelled "hard" are definitely still doable; they just require more materials or time than most of these other science experiments for kids.

#1: Insect Hotels

• Teaches Kids About: Zoology
• Difficulty Level: Medium
• Messiness Level: Medium

Insect hotels can be as simple (just a few sticks wrapped in a bundle) or as elaborate as you'd like, and they're a great way for kids to get creative making the hotel and then get rewarded by seeing who has moved into the home they built. After creating a hotel with hiding places for bugs, place it outside (near a garden is often a good spot), wait a few days, then check it to see who has occupied the "rooms." You can also use a bug ID book or app to try and identify the visitors.

• Materials Needed
• Shadow box or other box with multiple compartments
• Hot glue gun with glue
• Sticks, bark, small rocks, dried leaves, bits of yarn/wool, etc.

#2: DIY Lava Lamp

• Teaches Kids About: Chemical reactions
• Difficulty Level: Easy

In this quick and fun science experiment, kids will mix water, oil, food coloring, and antacid tablets to create their own (temporary) lava lamp . Oil and water don't mix easily, and the antacid tablets will cause the oil to form little globules that are dyed by the food coloring. Just add the ingredients together and you'll end up with a homemade lava lamp!

• Vegetable oil
• Food coloring
• Antacid tablets

#3: Magnetic Slime

• Teaches Kids About: Magnets
• Messiness Level: High (The slime is black and will slightly dye your fingers when you play with it, but it washes off easily.)

A step up from silly putty and Play-Doh, magnetic slime is fun to play with but also teaches kids about magnets and how they attract and repel each other. Some of the ingredients you aren't likely to have around the house, but they can all be purchased online. After mixing the ingredients together, you can use the neodymium magnet (regular magnets won't be strong enough) to make the magnetic slime move without touching it!

• Liquid starch
• Adhesive glue
• Iron oxide powder
• Neodymium (rare earth) magnet

#4: Baking Soda Volcanoes

• Teaches Kids About: Chemical reactions, earth science
• Difficulty Level: Easy-medium
• Messiness Level: High

Baking soda volcanoes are one of the classic science projects for kids, and they're also one of the most popular. It's hard to top the excitement of a volcano erupting inside your home. This experiment can also be as simple or in-depth as you like. For the eruption, all you need is baking soda and vinegar (dishwashing detergent adds some extra power to the eruption), but you can make the "volcano" as elaborate and lifelike as you wish.

• Baking soda
• Dishwashing detergent
• Large mason jar or soda bottle
• Playdough or aluminum foil to make the "volcano"
• Additional items to place around the volcano (optional)
• Food coloring (optional)

#5: Tornado in a Jar

• Teaches Kids About: Weather
• Messiness Level: Low

This is one of the quick and easy and science experiments for kids to teach them about weather. It only takes about five minutes and a few materials to set up, but once you have it ready you and your kids can create your own miniature tornado whose vortex you can see and the strength of which you can change depending on how quickly you swirl the jar.

• Glitter (optional)

#6: Colored Celery Experiment

• Teaches Kids About: Plants

This celery science experiment is another classic science experiment that parents and teachers like because it's easy to do and gives kids a great visual understanding of how transpiration works and how plants get water and nutrients. Just place celery stalks in cups of colored water, wait at least a day, and you'll see the celery leaves take on the color of the water. This happens because celery stalks (like other plants) contain small capillaries that they use to transport water and nutrients throughout the plant.

• Celery stalks (can also use white flowers or pale-colored cabbage)

#7: Rain Cloud in a Jar

This experiment teaches kids about weather and lets them learn how clouds form by making their own rain cloud . This is definitely a science project that requires adult supervision since it uses boiling water as one of the ingredients, but once you pour the water into a glass jar, the experiment is fast and easy, and you'll be rewarded with a little cloud forming in the jar due to condensation.

• Glass jar with a lid
• Boiling water
• Aerosol hairspray

#8: Edible Rock Candy

• Teaches Kids About: Crystal formation

It takes about a week for the crystals of this rock candy experiment to form, but once they have you'll be able to eat the results! After creating a sugar solution, you'll fill jars with it and dangle strings in them that'll slowly become covered with the crystals. This experiment involves heating and pouring boiling water, so adult supervision is necessary, once that step is complete, even very young kids will be excited to watch crystals slowly form.

• Large saucepan
• Clothespins
• String or small skewers
• Candy flavoring (optional)

#9: Water Xylophone

• Teaches Kids About: Sound waves

With just some basic materials you can create your own musical instrument to teach kids about sound waves. In this water xylophone experiment , you'll fill glass jars with varying levels of water. Once they're all lined up, kids can hit the sides with wooden sticks and see how the itch differs depending on how much water is in the jar (more water=lower pitch, less water=higher pitch). This is because sound waves travel differently depending on how full the jars are with water.

• Wooden sticks/skewers

#10: Blood Model in a Jar

• Teaches Kids About: Human biology

This blood model experiment is a great way to get kids to visual what their blood looks like and how complicated it really is. Each ingredient represents a different component of blood (plasma, platelets, red blood cells, etc.), so you just add a certain amount of each to the jar, swirl it around a bit, and you have a model of what your blood looks like.

• Empty jar or bottle
• Red cinnamon candies
• Marshmallows or dry white lima beans
• White sprinkles

#11: Potato Battery

• Teaches Kids About: Electricity
• Difficulty Level: Hard

Did you know that a simple potato can produce enough energy to keep a light bulb lit for over a month? You can create a simple potato battery to show kids. There are kits that provide all the necessary materials and how to set it up, but if you don't purchase one of these it can be a bit trickier to gather everything you need and assemble it correctly. Once it's set though, you'll have your own farm grown battery!

• Fresh potato
• Galvanized nail
• Copper coin

#12: Homemade Pulley

• Teaches Kids About: Simple machines

This science activity requires some materials you may not already have, but once you've gotten them, the homemade pulley takes only a few minutes to set up, and you can leave the pulley up for your kids to play with all year round. This pulley is best set up outside, but can also be done indoors.

• Clothesline
• 2 clothesline pulleys

#13: Light Refraction

• Teaches Kids About: Light

This light refraction experiment takes only a few minutes to set up and uses basic materials, but it's a great way to show kids how light travels. You'll draw two arrows on a sticky note, stick it to the wall, then fill a clear water bottle with water. As you move the water bottle in front of the arrows, the arrows will appear to change the direction they're pointing. This is because of the refraction that occurs when light passes through materials like water and plastic.

• Sticky note
• Transparent water bottle

#14: Nature Journaling

• Teaches Kids About: Ecology, scientific observation

A nature journal is a great way to encourage kids to be creative and really pay attention to what's going on around them. All you need is a blank journal (you can buy one or make your own) along with something to write with. Then just go outside and encourage your children to write or draw what they notice. This could include descriptions of animals they see, tracings of leaves, a drawing of a beautiful flower, etc. Encourage your kids to ask questions about what they observe (Why do birds need to build nests? Why is this flower so brightly colored?) and explain to them that scientists collect research by doing exactly what they're doing now.

• Blank journal or notebook
• Pens/pencils/crayons/markers
• Tape or glue for adding items to the journal

#15: DIY Solar Oven

• Teaches Kids About: Solar energy

This homemade solar oven definitely requires some adult help to set up, but after it's ready you'll have your own mini oven that uses energy from the sun to make s'mores or melt cheese on pizza. While the food is cooking, you can explain to kids how the oven uses the sun's rays to heat the food.

• Aluminum foil
• Knife or box cutter
• Permanent marker
• Plastic cling wrap
• Black construction paper

#16: Animal Blubber Simulation

• Teaches Kids About: Ecology, zoology

If your kids are curious about how animals like polar bears and seals stay warm in polar climates, you can go beyond just explaining it to them; you can actually have them make some of their own blubber and test it out. After you've filled up a large bowl with ice water and let it sit for a few minutes to get really cold, have your kids dip a bare hand in and see how many seconds they can last before their hand gets too cold. Next, coat one of their fingers in shortening and repeat the experiment. Your child will notice that, with the shortening acting like a protective layer of blubber, they don't feel the cold water nearly as much.

• Bowl of ice water

#17: Static Electricity Butterfly

This experiment is a great way for young kids to learn about static electricity, and it's more fun and visual than just having them rub balloons against their heads. First you'll create a butterfly, using thick paper (such as cardstock) for the body and tissue paper for the wings. Then, blow up the balloon, have the kids rub it against their head for a few seconds, then move the balloon to just above the butterfly's wings. The wings will move towards the balloon due to static electricity, and it'll look like the butterfly is flying.

• Tissue paper
• Thick paper
• Glue stick/glue

#18: Edible Double Helix

• Teaches Kids About: Genetics

If your kids are learning about genetics, you can do this edible double helix craft to show them how DNA is formed, what its different parts are, and what it looks like. The licorice will form the sides or backbone of the DNA and each color of marshmallow will represent one of the four chemical bases. Kids will be able to see that only certain chemical bases pair with each other.

• 2 pieces of licorice
• 12 toothpicks
• Small marshmallows in 4 colors (9 of each color)
• 5 paperclips

#19: Leak-Proof Bag

• Teaches Kids About: Molecules, plastics

This is an easy experiment that'll appeal to kids of a variety of ages. Just take a zip-lock bag, fill it about ⅔ of the way with water, and close the top. Next, poke a few sharp objects (like bamboo skewers or sharp pencils) through one end and out the other. At this point you may want to dangle the bag above your child's head, but no need to worry about spills because the bag won't leak? Why not? It's because the plastic used to make zip-lock bags is made of polymers, or long chains of molecules that'll quickly join back together when they're forced apart.

• Zip-lock bags
• Objects with sharp ends (pencils, bamboo skewers, etc.)

#20: How Do Leaves Breathe?

• Teaches Kids About: Plant science

It takes a few hours to see the results of this leaf experiment , but it couldn't be easier to set up, and kids will love to see a leaf actually "breathing." Just get a large-ish leaf, place it in a bowl (glass works best so you can see everything) filled with water, place a small rock on the leaf to weigh it down, and leave it somewhere sunny. Come back in a few hours and you'll see little bubbles in the water created when the leaf releases the oxygen it created during photosynthesis.

• Large bowl (preferably glass)
• Magnifying glass (optional)

#21: Popsicle Stick Catapults

Kids will love shooting pom poms out of these homemade popsicle stick catapults . After assembling the catapults out of popsicle sticks, rubber bands, and plastic spoons, they're ready to launch pom poms or other lightweight objects. To teach kids about simple machines, you can ask them about how they think the catapults work, what they should do to make the pom poms go a farther/shorter distance, and how the catapult could be made more powerful.

• Popsicle sticks
• Rubber bands
• Plastic spoons
• Paint (optional)

#22: Elephant Toothpaste

You won't want to do this experiment near anything that's difficult to clean (outside may be best), but kids will love seeing this " elephant toothpaste " crazily overflowing the bottle and oozing everywhere. Pour the hydrogen peroxide, food coloring, and dishwashing soap into the bottle, and in the cup mix the yeast packet with some warm water for about 30 seconds. Then, add the yeast mixture to the bottle, stand back, and watch the solution become a massive foamy mixture that pours out of the bottle! The "toothpaste" is formed when the yeast removed the oxygen bubbles from the hydrogen peroxide which created foam. This is an exothermic reaction, and it creates heat as well as foam (you can have kids notice that the bottle became warm as the reaction occurred).

• Clean 16-oz soda bottle
• 6% solution of hydrogen peroxide
• 1 packet of dry yeast
• Dishwashing soap

#23: How Do Penguins Stay Dry?

Penguins, and many other birds, have special oil-producing glands that coat their feathers with a protective layer that causes water to slide right off them, keeping them warm and dry. You can demonstrate this to kids with this penguin craft by having them color a picture of a penguin with crayons, then spraying the picture with water. The wax from the crayons will have created a protective layer like the oil actual birds coat themselves with, and the paper won't absorb the water.

• Penguin image (included in link)
• Spray bottle
• Blue food coloring (optional)

#24: Rock Weathering Experiment

• Teaches Kids About: Geology

This mechanical weathering experiment teaches kids why and how rocks break down or erode. Take two pieces of clay, form them into balls, and wrap them in plastic wrap. Then, leave one out while placing the other in the freezer overnight. The next day, unwrap and compare them. You can repeat freezing the one piece of clay every night for several days to see how much more cracked and weathered it gets than the piece of clay that wasn't frozen. It may even begin to crumble. This weathering also happens to rocks when they are subjected to extreme temperatures, and it's one of the causes of erosion.

• Plastic wrap

#25: Saltwater Density

• Teaches Kids About: Water density

For this saltwater density experiment , you'll fill four clear glasses with water, then add salt to one glass, sugar to one glass, and baking soda to one glass, leaving one glass with just water. Then, float small plastic pieces or grapes in each of the glasses and observe whether they float or not. Saltwater is denser than freshwater, which means some objects may float in saltwater that would sink in freshwater. You can use this experiment to teach kids about the ocean and other bodies of saltwater, such as the Dead Sea, which is so salty people can easily float on top of it.

• Four clear glasses
• Lightweight plastic objects or small grapes

#26: Starburst Rock Cycle

With just a package of Starbursts and a few other materials, you can create models of each of the three rock types: igneous, sedimentary, and metamorphic. Sedimentary "rocks" will be created by pressing thin layers of Starbursts together, metamorphic by heating and pressing Starbursts, and igneous by applying high levels of heat to the Starbursts. Kids will learn how different types of rocks are forms and how the three rock types look different from each other.

• Toaster oven

#27: Inertia Wagon Experiment

• Teaches Kids About: Inertia

This simple experiment teaches kids about inertia (as well as the importance of seatbelts!). Take a small wagon, fill it with a tall stack of books, then have one of your children pull it around then stop abruptly. They won't be able to suddenly stop the wagon without the stack of books falling. You can have the kids predict which direction they think the books will fall and explain that this happens because of inertia, or Newton's first law.

• Stack of books

#28: Dinosaur Tracks

• Teaches Kids About: Paleontology

How are some dinosaur tracks still visible millions of years later? By mixing together several ingredients, you'll get a claylike mixture you can press your hands/feet or dinosaur models into to make dinosaur track imprints . The mixture will harden and the imprints will remain, showing kids how dinosaur (and early human) tracks can stay in rock for such a long period of time.

• Used coffee grounds
• Wooden spoon
• Rolling pin

#29: Sidewalk Constellations

• Teaches Kids About: Astronomy

If you do this sidewalk constellation craft , you'll be able to see the Big Dipper and Orion's Belt in the daylight. On the sidewalk, have kids draw the lines of constellations (using constellation diagrams for guidance) and place stones where the stars are. You can then look at astronomy charts to see where the constellations they drew will be in the sky.

• Sidewalk chalk
• Small stones
• Diagrams of constellations

#30: Lung Model

By building a lung model , you can teach kids about respiration and how their lungs work. After cutting off the bottom of a plastic bottle, you'll stretch a balloon around the opened end and insert another balloon through the mouth of the bottle. You'll then push a straw through the neck of the bottle and secure it with a rubber band and play dough. By blowing into the straw, the balloons will inflate then deflate, similar to how our lungs work.

• Plastic bottle
• Rubber band

#31: Homemade Dinosaur Bones

By mixing just flour, salt, and water, you'll create a basic salt dough that'll harden when baked. You can use this dough to make homemade dinosaur bones and teach kids about paleontology. You can use books or diagrams to learn how different dinosaur bones were shaped, and you can even bury the bones in a sandpit or something similar and then excavate them the way real paleontologists do.

• Images of dinosaur bones

#32: Clay and Toothpick Molecules

There are many variations on homemade molecule science crafts . This one uses clay and toothpicks, although gumdrops or even small pieces of fruit like grapes can be used in place of clay. Roll the clay into balls and use molecule diagrams to attach the clay to toothpicks in the shape of the molecules. Kids can make numerous types of molecules and learn how atoms bond together to form molecules.

• Clay or gumdrops (in four colors)
• Diagrams of molecules

#33: Articulated Hand Model

By creating an articulated hand model , you can teach kids about bones, joints, and how our hands are able to move in many ways and accomplish so many different tasks. After creating a hand out of thin foam, kids will cut straws to represent the different bones in the hand and glue them to the fingers of the hand models. You'll then thread yarn (which represents tendons) through the straws, stabilize the model with a chopstick or other small stick, and end up with a hand model that moves and bends the way actual human hands do.

• Straws (paper work best)
• Twine or yarn

#34: Solar Energy Experiment

• Teaches Kids About: Solar energy, light rays

This solar energy science experiment will teach kids about solar energy and how different colors absorb different amounts of energy. In a sunny spot outside, place six colored pieces of paper next to each other, and place an ice cube in the middle of each paper. Then, observe how quickly each of the ice cubes melt. The ice cube on the black piece of paper will melt fastest since black absorbs the most light (all the light ray colors), while the ice cube on the white paper will melt slowest since white absorbs the least light (it instead reflects light). You can then explain why certain colors look the way they do. (Colors besides black and white absorb all light except for the one ray color they reflect; this is the color they appear to us.)

• 6 squares of differently colored paper/cardstock (must include black paper and white paper)

#35: How to Make Lightning

• Teaches Kids About: Electricity, weather

You don't need a storm to see lightning; you can actually create your own lightning at home . For younger kids this experiment requires adult help and supervision. You'll stick a thumbtack through the bottom of an aluminum tray, then stick the pencil eraser to the pushpin. You'll then rub the piece of wool over the aluminum tray, and then set the tray on the Styrofoam, where it'll create a small spark/tiny bolt of lightning!

• Pencil with eraser
• Aluminum tray or pie tin
• Styrofoam tray

#36: Tie-Dyed Milk

• Teaches Kids About: Surface tension

For this magic milk experiment , partly fill a shallow dish with milk, then add a one drop of each food coloring color to different parts of the milk. The food coloring will mostly stay where you placed it. Next, carefully add one drop of dish soap to the middle of the milk. It'll cause the food coloring to stream through the milk and away from the dish soap. This is because the dish soap breaks up the surface tension of the milk by dissolving the milk's fat molecules.

• Shallow dish
• Milk (high-fat works best)

#37: How Do Stalactites Form?

Have you ever gone into a cave and seen huge stalactites hanging from the top of the cave? Stalactites are formed by dripping water. The water is filled with particles which slowly accumulate and harden over the years, forming stalactites. You can recreate that process with this stalactite experiment . By mixing a baking soda solution, dipping a piece of wool yarn in the jar and running it to another jar, you'll be able to observe baking soda particles forming and hardening along the yarn, similar to how stalactites grow.

• Safety pins
• 2 glass jars

Summary: Cool Science Experiments for Kids

Any one of these simple science experiments for kids can get children learning and excited about science. You can choose a science experiment based on your child's specific interest or what they're currently learning about, or you can do an experiment on an entirely new topic to expand their learning and teach them about a new area of science. From easy science experiments for kids to the more challenging ones, these will all help kids have fun and learn more about science.

What's Next?

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Christine graduated from Michigan State University with degrees in Environmental Biology and Geography and received her Master's from Duke University. In high school she scored in the 99th percentile on the SAT and was named a National Merit Finalist. She has taught English and biology in several countries.

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