rock candy crystals science experiment

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How to Make Rock Candy or Sugar Crystals

Sugar crystals are called rock candy because these hard crystals are edible. Sugar (sucrose) crystals are one of the few types of crystals you can grow and eat. You can eat the natural clear crystals or you can color and flavor them.

Rock Candy Materials

You only need a few common kitchen materials for this crystal project:

• 3 cups sugar (sucrose)
• 1 cup boiling water
• food coloring (optional)
• flavoring (optional — good choices include cherry, peppermint, and cinnamon)
• clean glass or plastic jar
• wooden skewer or cotton string

You don’t need string or a skewer to grow sugar crystals, but they are good support structures for making rock candy sticks. Crystals also grow on pipe cleaners, but they probably aren’t food-friendly. The crystals also grow on the bottom and sides of their container, forming a confection that is known as Misri in India and Iran.

You can use different kinds of sugar, but avoid powdered sugar because it often contains anti-caking agents. Anti-caking agents don’t dissolve, so the tiny particles attract crystal growth. While this sounds like a good things, it means you’ll get a mass of small crystals rather than large crystals.

Grow Sugar Crystals

The procedure is really easy.

• Dissolve the sugar in the boiling water. Heat the sugar solution on the stove, or in the microwave if you have trouble getting the sugar to dissolve. Once the sugar dissolves, remove it from heat. If you keep heating it, it hardens and burns.
• Add a few drops of food coloring and flavor, if desired.
• Let the solution cool a bit before pouring it into your jar. You don’t want to get burned!
• Pour the sugar solution into a jar. Place a wooden skewer into the jar or else hang a string into the middle of the jar, tied to a pencil or butter knife.
• Place the container somewhere it won’t be disturbed. If you like, cover the jar with a paper towel or coffee filter to allow evaporation while keeping the crystal solution clean.
• It takes a few days to get good crystal growth. If you see crystals forming on the top of the jar, you can remove them and eat them. If you leave them, these crystals will compete with your stick or string for sugar and will reduce the size of your crystals.
• Remove the crystals and enjoy them! If you want to store the crystals before eating them, keep them in an airtight container so humidity in the air won’t make the rock candy sticky.

If you enjoyed growing sugar crystals, how about trying another easy crystal-growing project ?

How Long Does It Take to Grow Sugar Crystals?

Sugar crystals may appear overnight or it may take several days (weeks) for growth. Sugar crystal growth depends on three main factors:

• Solution Concentration : Crystals don’t start growing until you have a saturated solution , where no more sugar dissolves in the water. Whether or not the liquid is saturated depends on the amount of sugar in the water and the temperature. If you aren’t seeing crystal growth, try lowering the temperature. Refrigeration might do the trick!
• Temperature : Temperature determines when crystals start growing and how big they are. Slow cooling resulting in slower growth, but larger crystal formation. Similarly, quick cooling promotes crystal growth, but you get a mass of smaller crystals. Ideally, slowly cool the hot sugar water down to room temperature (or lower). Quick cooling doesn’t yield great results. Putting the liquid in a window causes temperature fluctuations, so crystals dissolve when it’s warm and form when it’s cool. Avoid the window.
• Humidity : Humid air contributes water to the liquid and slows crystal growth. Dry air evaporates water and aids crystal growth. If you aren’t seeing crystals, try improving air circulation or reducing humidity. The easiest solution is turning on a fan.

About Sugar Crystals

The white granular sugar you buy at the store is sucrose (C 12 H 22 O 11 ), which is a disaccharide consisting of glucose and fructose subunits. Raw sugar is usually golden or brown and contains some natural impurities, but still crystallizes. However, while pure sugar crystals are colorless, raw sugar crystals retain their color.

Sucrose contains covalent bonds and crystallizes using these bonds, too. The molecule crystalizes in the monoclinic space group. The resulting crystal is hard, brittle, and rigid. Examples of other crystals that contain covalent bonds are quartz and diamond.

• Beevers, C. A.; McDonald, T. R. R.; Robertson, J. H.; Stern, F. (1952). “The crystal structure of sucrose”. Acta Crystallogr . 5 (5): 689–90. doi: 10.1107/S0365110X52001908
• Hynes, R. C.; Le Page, Y. (1991). “Sucrose, a convenient test crystal for absolute structures”. Journal of Applied Crystallography . 24 (4): 352. doi: 10.1107/S0021889891002492
• Richardson, Tim (2002). Sweets: A History of Candy . Bloomsbury. ISBN 978-1-58234-229-0.

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Rock Candy Science Experiment: Step-by-Step How-To Guide

By: Author Hess UnAcademy Team

Posted on Last updated: September 18, 2023

Are you on the lookout for exciting and educational activities to enjoy with your curious little ones? Are your kids looking for a fun indoor activity that couples the wonders of science with the joys of eating? Well, we’ve got a treat for you—literally! A DIY rock candy science experiment is the perfect activity.

Homemade rock candy is a good example of a kid-friendly edible science experiment and it’s an example of an easy way to make homeschooling fun . It’s a fantastic hands-on activity that combines the joy of making delicious treats with the wonders of scientific discovery. Trust us, your kids will be buzzing with excitement, and you’ll be their official hero of the day!

Finding engaging and educational experiments can be a challenge. Sure, there’s no shortage of ideas out there, but finding the perfect balance between fun and learning can sometimes feel like searching for a needle in a haystack.

That’s why we’re share this rock candy science experiment—a delightful way to pique your child’s interest in science while indulging their sweet tooth.

Imagine watching your little ones’ eyes light up as they witness the magical transformation of simple ingredients into mouthwatering rock candy crystals. Not only will they be fascinated by the process, but they’ll also be absorbing essential scientific concepts without even realizing it. From crystallization to supersaturation, this experiment is a fantastic opportunity to spark their curiosity and set them on a path to becoming budding scientists.

Plus, let’s not forget about the joy of spending quality time with your kids. With the rock candy science experiment, you’ll be able to create lifelong memories as you bond over a shared love of exploration and delicious treats (adult supervision highly recommended). Whether it’s a rainy day activity or a weekend adventure, this experiment is sure to bring smiles, laughter, and a healthy dose of sugar-induced happiness to your household.

So, are you ready to dive into the captivating world of rock candy science? Stick around as we guide you through this step-by-step how-to guide, ensuring that you and your little scientists have a blast every step of the way. Get ready to transform ordinary sugar into a dazzling crystal creation that will not only satisfy their taste buds but also ignite their passion for learning. Let’s embark on this sweet journey together!

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DIY Rock Candy Science Experiment

My kids have always loved eating rock candy, but it never occurred to me to let them make some themselves. But the other day, I got a text from my sister-in-law with pictures of my cute little niece and nephew enjoying their own homemade rock candy. My other sister-in-law responded saying how fun that looked and she’d like to try it with her own daughter.

My kids, of course, didn’t want to be left out and asked to make their own rock candy. And I, being the awesomely fantastic homeschooling mom that I am, told them I’d do them one better. I told them we could turn a homemade rock candy adventure into a full-on DIY homemade rock candy science project, with the scientific method and everything!

The kids were thrilled. Anything to get them another dose of sweets, am I right?

STEAM activities are very popular in our household as is, but this one, in particular, was especially fun.

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DIY Homemade Rock Candy Science Project

Because we wanted to use this science project to teach our kids the scientific method, we started by gathering them all together and having them decide what they wanted to learn or discover. What questions did they want to ask?

If you turn this adventure into a science project, you’ll want your kids to come up with a couple of questions as well. I made these handy scientific method worksheets for you to print off and use if you want, or you can use a notebook.

These are some of our favorite printable worksheets for kids so don’t miss out!

A few examples of questions we gave our kids include:

• What happens when you put a string in a high sugar concentrated solution?
• If food coloring is added to the solution will it change the result?
• Can layers of color be made with the candy?
• Can you add flavors beyond the straight sugar?
• Will a Kool-Aid solution do both color and flavor?
• Can you do crystals in a spherical setting like a chocolate ball?
• Does the ball need to be turned or stationary in the crystallization process…which gives a better result?
• Can you make a stalagmite candy with the same concept only in reverse?
• Will the results change if I use powdered sugar or brown sugar instead of granulated sugar?
• Will the results change if the string or stick starts out wet vs dry?
• Will sugar crystals grow if I use a sugar-water solution that has not been boiled (supersaturated solution)?

These are of course merely examples. Let your kids get creative and exercise their scientific minds! And don’t worry if a few kids pick duplicate questions, or if everybody picks the same. The real lesson here is the process.

NOTE – We plan on continuing this experiment over the course of the next year or so, updating it periodically as we experiment with other questions.

Our kids decided to answer the following questions:

• Spencer wanted to know if he could make stalactites and stalagmites out of sugar crystals.
• Nicole wanted to experiment with flavors and see what the difference is between plain rock candy crystals and flavored. She made a plain solution and one with vanilla extract.
• Eugene was very confused about the whole process and couldn’t grasp what we were trying to do, so he asked the question, “Will sugar crystals grow better with a supersaturated solution made from boiling water, or with the same ratio of sugar to water, but without the boiling?”
• Jennifer wanted to experiment with kool-aid and wanted to see if mixing kool-aid in the sugar-water solution would make flavored and colored rock candy crystals.

Now let the experiment begin!

How To Make Homemade Rock Candy

Ingredients For Homemade Rock Candy

• 2 Cups of water
• 6 Cups of sugar (white, granulated) plus some spare
• Optional – Food coloring (2 drops of food coloring per jar/cup)
• Optional – Flavoring extract (1 tsp)

Other Needed Materials

• Clean containers such as cups or mason jars
• Something to grow sugar crystals on, such as some string or a wooden skewer
• Something to hold the thing your crystals form on away from sides of the jar and bottom of the jar, such as a pencil or some clothespins
• Mixing spoon

Instructions For Making Rock Candy

• Make sure you gather your tools beforehand. You don’t want to let your sugar solution cool before you are ready.
• Put each measuring cup of water in the pot and heat it to boiling. Make sure your pot has a lot of space because the solution will expand quite a bit.
• Once you have boiling water, begin adding granulated sugar a little at a time.
• Keep mixing and heating until the sugar is completely dissolved. This took us about 20 minutes.
• Once the sugar is dissolved, divide your supersaturated solution into each cup or glass jar.
• Add your flavoring and/or your coloring now! Not too much, and make sure you mix well.
• Dip your string or wooden skewer into the supersaturated solution. Anchor it to the top of the container somehow. We used a string and a paperclip. Make sure the string isn’t touching the sides of the jar or the bottom of the jar .
• Put your sugar-water solution somewhere safe to sit for a few days. Watch and wait for your sugar crystals to grow. These are your rock candy crystals.
• It is unclear how long you need to let your sugar crystals grow for. Some of our cups had crystals after 2 days, others still looked pitiful after an entire week. My dad says when he was a kid, they used to wait for a month. I would recommend using seed crystals by rolling your (wet) string or skewer in granulated sugar before putting it in your supersaturated solution and see if that speeds things up.
• Enjoy your delicious food science project of homemade rock candy.

Our Rock Candy Science Project Results

Spencer (age 10) asked the following question: Can I make stalagmites and stalactites out of sugar crystals by hanging an absorbent material from one cup of sugar solution to another?

THE RESULTS: Using a sugar to water ratio of 3:1 with a strip of cotton fabric did not create stalagmites or stalactites. The cotton strip did not absorb sugar solution fast enough to get it dripping. I wonder if a ratio of 2:1 would work better? It’s also possible the cups were not filled enough. We will try this again.

As you can see, he still got some great candy crystals out of the experiment, the solution just didn’t crawl up the cloth and make crystal drippings.

Nicole (age 9) asked the following question: Can I flavor my sugar crystals by adding vanilla extract right before letting the rock candy crystals grow?

THE RESULTS: Yes,adding about 1 tsp of vanilla extract to the sugar solution after it has been boiled added a nice vanilla flavoring to the finished rock candy. I wonder what other flavors I could make in the future?

Eugene (age 7) asked the following question: Can I make sugar crystals without boiling the water and sugar solution?

THE RESULTS: No, merely mixing water and sugar without boiling will not create an environment that sugar crystals can grow in. It is important to make a supersaturated solution by boiling the water with the sugar.

Jennifer (age 6) asked the following question: Can I use Kool-Aid (or powdered other drink mix) to change the color and the flavor of my rock candy at the same time?

THE RESULTS: Yes, Kool-Aid (or other powdered drink mixes) will change the color and the flavor of the rock candy, while still allowing sugar crystals to grow. I wonder what other things I could add to the sugar crystals, such as soda for example, without killing the crystals?

Rock Candy Science Fair Project Explained

If you want to use this experiment as a science fair project, or if you want to teach your kids the why behind the experiment, I’ve explained it below.

When you first combined the boiling water with the multiple cups of sugar, you created a supersaturated solution of sugar-water. When the sugar-water is supersaturated like this, the water can only properly mix with (and hold) the sugar when both are very hot (boiling water and sugar).

As the hot water begins to cool it can no longer hold the sugar so the supersaturated solution begins to separate and the sugar crystals begin to cling to your skewer or string.

The sugar molecules that were originally on the string/skewer will act as seed crystals, where more sugar molecules from the sugar solution will cling until sugar crystals begin to grow. Some crystal growth will even happen on the side of the jar.

Feel free to use this activity as a simple science fair project . Your peers will be impressed with this tasty scientific experiment.

Or if you’re looking for another fun science project idea, what about something involving the science of slime ?

Enjoy making your very own edible rock candy science experiment!

And remember to grab your free worksheets!

STEM Resources Delivered to Your Inbox Every Month

If you liked this edible STEM activity, you are going to love the STEM Made Easy Digital Subscription . Each month, you’ll receive 5 fully-planned STEM project guides along with worksheets and instructions for how to make them fun and engaging for kids ages 3-19. Check it out now !

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Homemade Rock Candy is science you can eat!

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Sugar Crystal Experiment

This is an absolutely sweet science experiment! Grow sugar crystals and make homemade rock candy with this simple chemistry experiment. We can show you how to set up a science fair project to go along with it! Growing sugar crystals is a fun and easy science experiment for kids. .

Incredible Edible Science

Who doesn’t love science you can eat ? Grow sugar crystals for tasty chemistry , and the kids will have a blast learning all about crystals!

Crystal science has fascinated humans for thousands of years. Many of our precious gemstones are formations of crystal. Check out other crystal science projects like our salt crystals and borax crystals. You can also make edible rock candy geodes .

This sugar crystal experiment uses the same saturation principles and makes a saturated solution to form the crystals. Growing crystals is fun for kids and teaches them about solutions, molecular bonds, patterns, and energy. All from two ingredients: sugar and water!

Oh, and of course, you can incorporate it into a geology lesson , too!

💡 You can eat these crystals when you are done growing them, making it even more fun!

How to Grow Sugar Crystals

Why do we call chemistry experiments like this kitchen science ? It is because all the needed supplies come straight out of the kitchen. Easy!

Note: You will need to set aside 8+ days to complete this sugar crystal experiment.

• 1 cup water
• 4 cups sugar
• Edible glitter
• Food coloring

Also check out more fun ideas for mason jar science! Once you set up your sugar crystal experiment, try a few more quick science in a jar ideas!

HOW TO MAKE SUGAR CRYSTALS

STEP 1. The day before starting your sugar crystal experiment, cut a piece of string a little longer than your jars. Tie one end of the string to a straw. Tie a knot in the other end.

Get the strings wet and coat them in sugar. Let them dry overnight.

STEP 2.   Add four cups of sugar and one cup of water to a saucepan the following day and heat until boiling. Heating the water to dissolve the sugar is the key to making your supersaturated solution.

Create the sugar solution: Heat water in a saucepan until it just begins to boil. Remove the saucepan from the heat. Add granulated sugar to the hot water, stirring continuously, until no more sugar dissolves. Keep adding sugar and stirring until you see some sugar settling at the bottom of the saucepan without dissolving further. This indicates that you have a saturated solution.

STEP 3. Pour your sugar mixture into the jars. Add edible food coloring to each jar and add some edible glitter.

STEP 4. Lower the string into the jar and place the jars in a safe place. Leave the sugar crystals to form for at least a week.

SUGAR CRYSTALS: DAY 8

Once the sugar crystals are as big as you want them, remove them from the sugar solution. Lay them on a paper towel or plate and let them dry for several hours.

Inspect the sugar crystals with a magnifying glass or microscope when they are dry . How are the crystals similar? How are they different? What can you see in the microscope or with a magnifying glass that you can’t see with your eyes?

Fabulous, edible science is at your fingertips when you explore science in the kitchen with your kids!

FREE Geology Activities Guide

Just because it’s food or candy doesn’t mean you can’t apply the scientific method .

Sugar Crystal Science Fair Projects

Science projects are an excellent way for older kids to show what they know about science. They can also be used in various environments, including classrooms, homeschooling, clubs, and groups.

💡 Kids can take everything they have learned about using the scientific method , stating a hypothesis, creating variables , and analyzing and presenting data.

Want to turn this sugar crystals experiment into a cool sugar crystallization science project? Check out these helpful resources below. Take a look at the science fair project outline below to get started.

• Science Project Tips From A Teacher
• Science Fair Board Ideas
• Easy Science Fair Projects

Sample Science Procedure to Grow Sugar Crystals:

• Begin the project by explaining what crystals are and the process of crystallization. Take a look at different examples of sugar crystals to learn more.
• Formulate a hypothesis. For example, “I predict that crystals will grow faster/bigger in a solution with more sugar.”
• Prepare the different containers for growing crystals according to the steps above.
• Encourage kids to set up multiple containers with different variables to test.
• a. Vary the sugar concentration in the solution (e.g., 1 cup sugar:1 cup water, 1 cup sugar:1/2 cup water, etc.).
• b. Compare different types of sugar (granulated sugar, powdered sugar, brown sugar).
• c. Test the effect of temperature by placing one container in the fridge and another in a warm place. d. Investigate the impact of time by checking the crystals’ growth at regular intervals (e.g., every day for a week).
• Have the kids observe the containers regularly and record them in a notebook. They should note changes in crystal size, shape, and formation patterns. Use our free science fair pack to help!
• Help the kids analyze their results and draw conclusions based on their observations.
• Discuss whether their hypotheses were supported and if they noticed any unexpected findings.
• Prepare a display board for the science fair, showcasing the experiment’s steps, observations, and results.

This project provides an excellent opportunity for kids to learn about the scientific method, observation, and the fascinating world of crystal formation while enjoying some sweet treats!

More Fun Edible Experiments

See if you can turn one of these science experiments into a science fair project!

• Strawberry DNA Extraction (not edible, but a great project)
• Make Edible Geodes
• Fizzing Lemonade
• Maple Syrup Snow Candy
• Homemade Butter
• Ice Cream In A Bag

Printable Science Projects For Kids

If you’re looking to grab all of our printable science projects in one convenient place plus exclusive worksheets and bonuses like a STEAM Project pack, our Science Project Pack is what you need! Over 300+ Pages!

• 90+ classic science activities  with journal pages, supply lists, set up and process, and science information.  NEW! Activity-specific observation pages!
• Best science practices posters  and our original science method process folders for extra alternatives!
• Be a Collector activities pack  introduces kids to the world of making collections through the eyes of a scientist. What will they collect first?
• Know the Words Science vocabulary pack  includes flashcards, crosswords, and word searches that illuminate keywords in the experiments!
• My science journal writing prompts  explore what it means to be a scientist!!
• Bonus STEAM Project Pack:  Art meets science with doable projects!
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