Make rock candy Follow FizzicsEd 150 Science Experiments: Comments 20 You will need: Adult Help 300g Of Sugar Saucepan or kettle with 500mL of water Wooden kebab stick or chopstick 2 Clothes pegs A glass A metal spoon A place to leave the experiment setup away from ants Optional: food colouring Written by Fizzics Education. Reviewed by Ben Newsome CF. Cite this experiment Copyright Notice Instruction 1 With adult help, carefully heat the water in a saucepan. You may want to add some food colouring as an optional extra too! 2 Stir in the sugar slowly, stirring constantly whilst the sugar dissolves. Keep adding sugar until you cannot dissolve the sugar crystals anymore. At this point just add a tiny bit more water and dissolve the leftover crystals as well. 3 Pour the saturated sugar solution carefully into a glass. 4 Using pegs to suspend a chopstick on the saturated sugar solution Use two clothes pegs to suspend the wooden kebab stick or chopstick in the sugar solution without the stick touching the sides of the glass. Place the glass in space where ants cannot get at it (you might want to cover the experiment with a cloth). 5 Multiple rock candy experiments You may want to setup several experiments to see if the crystal formation differs with different amounts of sugar in the water. It’s all about variable testing! 6 Rock candy beginning to grow on the chopstick Observe the experiment over several days, taking note of when crystals start to form. 7 Rock candy crystals Run the experiment until you have grown the large sugar crystals along the stick (without the crystals touching the side of the glass). 8 Get the Unit of Work on Mixtures here! How can we separate mixtures? What are the different techniques? From chromatography to magnetism, join us to explore the variety of ways we can separate mixtures! Includes cross-curricular teaching ideas, student quizzes, a sample marking rubric, scope & sequences & more 9 School science visits since 2004! – Curriculum-linked & award-winning incursions. – Over 40 primary & high school programs to choose from. – Designed by experienced educators. – Over 2 million students reached. – Face to face incursions & online programs available. – Early learning centre visits too! 10 Online courses for teachers & parents – Help students learn how science really works Why Does This Happen? The Science of Making Rock Candy In this experiment, you created a super-saturated solution! Ordinarily, water can only dissolve a certain amount of sugar at room temperature (this is the saturation point). However, by heating the water, the molecules move faster and spread further apart, allowing much more sugar to be dissolved than normal. As the solution cools down, it becomes unstable because it is holding more sugar than it “should” be able to at a lower temperature. This creates the perfect environment for crystallisation. Because you used a kebab stick (especially if it was pre-dusted with sugar), you provided nucleation points. These are microscopic rough spots or “seed crystals” that give the dissolved sugar molecules a place to latch onto and begin building a solid structure. The sugar molecules are more attracted to the rough surface of the stick than the smooth glass of the jar. Over several days, as the water slowly evaporates and the temperature remains cool, more and more molecules stack themselves onto the stick, causing your rock candy to grow larger and larger! A great rule of thumb in geology and chemistry is: the longer it takes to form a crystal, the larger the crystal will be. You can see this in everything from crystal growing kits to the way gemstones form deep underground! This also explains why liquid nitrogen ice-cream is so smooth—it freezes so fast that the ice crystals stay tiny. Learn how crystals are formed by volcanoes. Deep dive into the technical side of crystal seeding here. Variables to test Find out more on variables here. Solvent Temperature Try starting the experiment with hot versus cold water. How does the thermal energy change the amount of sugar the water can “hold” before it reaches saturation? Solute Concentration Vary the amount of sugar used. Is there a “magic ratio” that produces the fastest growth without the solution turning into a solid block? Liquid Medium What happens if you use other liquids like apple juice or tea? Different liquids have different chemical properties; do they help or hinder crystal growth? Substrate Texture Try different materials for the sugar to cling to, such as cotton string, a smooth plastic stick, or a rough wooden skewer. Which surface area provides the best nucleation points? Evaporation Rate If you cover the jar with a lid versus leaving it open, does the rate of evaporation change how quickly the crystals form? Remember, for a “fair test,” only change one variable at a time. Keeping everything else identical ensures that your results are valid and accurate! âś… Reviewed: April 6, 2026 APA 7 Citation: Fizzics Education. (2018). Sugar crystal rock candy. https://www.fizzicseducation.com.au/150-science-experiments/kitchen-chemistry-experiments/sugar-crystal-rock-candy/ Copy APA Citation Reviewer This resource was last reviewed for scientific accuracy on April 6, 2026. Ben Newsome CF is the recipient of the 2023 UTS Chancellor’s Award for Excellence and a Churchill Fellow. He is a global leader in science communication and the founder of Fizzics Education. Learn more! From crystal growing to slimy science, we’ve got your kitchen chemistry covered! Get in touch with FizzicsEd to find out how we can work with your class. Chemistry Show Years 3 to 6 Maximum 60 students Science Show (NSW & VIC) 60 minutes Online Class Available Read More Enquire Now Magic Crystal Tree Science Kit $4.95 excl. GST View Details Add to Cart Trustpilot STEM Full Day Accelerator - Primary Designed from real classroom experiences, this modular day helps you create consistently effective science learning that directly address the new curriculum with easily accessible and cost-effective materials. Read More Enquire Now Be Amazing! How to teach science, the way primary kids love. $29.95 excl. GST View Details Add to Cart Trustpilot
With adult help, carefully heat the water in a saucepan. You may want to add some food colouring as an optional extra too!
Stir in the sugar slowly, stirring constantly whilst the sugar dissolves. Keep adding sugar until you cannot dissolve the sugar crystals anymore. At this point just add a tiny bit more water and dissolve the leftover crystals as well.
Using pegs to suspend a chopstick on the saturated sugar solution Use two clothes pegs to suspend the wooden kebab stick or chopstick in the sugar solution without the stick touching the sides of the glass. Place the glass in space where ants cannot get at it (you might want to cover the experiment with a cloth).
Multiple rock candy experiments You may want to setup several experiments to see if the crystal formation differs with different amounts of sugar in the water. It’s all about variable testing!
Rock candy beginning to grow on the chopstick Observe the experiment over several days, taking note of when crystals start to form.
Rock candy crystals Run the experiment until you have grown the large sugar crystals along the stick (without the crystals touching the side of the glass).
Get the Unit of Work on Mixtures here! How can we separate mixtures? What are the different techniques? From chromatography to magnetism, join us to explore the variety of ways we can separate mixtures! Includes cross-curricular teaching ideas, student quizzes, a sample marking rubric, scope & sequences & more
School science visits since 2004! – Curriculum-linked & award-winning incursions. – Over 40 primary & high school programs to choose from. – Designed by experienced educators. – Over 2 million students reached. – Face to face incursions & online programs available. – Early learning centre visits too!
From crystal growing to slimy science, we’ve got your kitchen chemistry covered! Get in touch with FizzicsEd to find out how we can work with your class.
Chemistry Show Years 3 to 6 Maximum 60 students Science Show (NSW & VIC) 60 minutes Online Class Available Read More Enquire Now
STEM Full Day Accelerator - Primary Designed from real classroom experiences, this modular day helps you create consistently effective science learning that directly address the new curriculum with easily accessible and cost-effective materials. Read More Enquire Now
Designed from real classroom experiences, this modular day helps you create consistently effective science learning that directly address the new curriculum with easily accessible and cost-effective materials.
Be Amazing! How to teach science, the way primary kids love. $29.95 excl. GST View Details Add to Cart Trustpilot
This was pretty helpful. I’m glad this could help me for my science fair project but maybe you guys should include a little bit more on how they actually form and start to clump to the dowel or skewer. Thanks! Reply
Sure thing Amanda! It’s all about how rough the skewers are under a microscope. With super-saturated sugar solutions, the molecules of sugar more easily precipitate onto the rough surfaces of the kebab sticks than the smoother glass container. As the sugar molecules settle on the rough surfaces (also known as nucleation points), the crystallized sugar provides even more rough surfaces for the rest of the sugar to come out of solution. We’ve added a link into the post which takes to a detailed paper on seeding crystals too. Thanks for trying this science experiment, we’re glad that it helped your science fair project! Reply
Hi Ryan, great question! I want you to try several versions of thick vs thin (dense vs. less dense)… this way you’re doing real science and not just a trick 🙂 Once you know the answer, pop it in the chat below for everyone and you’ve helped everyone who reads your answer! Reply
Love your question Ryan! Just change the different amount of the sugar syrup that you add to glasses of the same size and then top up with water to the same level. A bit of a mix and you’ve changed the density by diluting the sugar solution for each glass. Reply
How long does it normally take? I’ve had it set up for almost 5 days now and there is little growth. Does it make a difference if we don’t boil the water? Reply
Hi Caitlin! This has a lot to do with how saturated your solution is as well as how rough the substrate is that the crystals are settling on. Generally, we see crystals from between 1 & 2 weeks however the longer you leave it, the larger the crystals will be. You can try boiling vs not boiling the water too as a fir test, let us know how this goes! Reply
Sure thing! Although you’ll find that the rock candy will be darker in colour. Let us know how you go 🙂 Reply
Hi Charlie, this is dependent on how dark you would like the rock candy to be. Generally you only need a few drops 🙂 Reply
Hi Lij, try different drops in different tests and see the difference! Here’s more about variable testing here Reply
Hi Ben, I was wondering if different types of liquids will impact the experiment. For example, cordial or lemon juice? Reply
Great question! I love this, please run the experiemnt and let us know (I could give the answer but I would love the students to explore this themselves). This experiement is about super saturation and nucleation sites; the lemon juice adds an interesting pH angle but technically you would need to know the amount of sugar in the lemon juice for this to be a fair test. And more boradly, lemon juice is more than just an acidic liquid, so the studnets could go deeper to see if there is something in the lemon juice making a difference. Reply
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