Rock Candy

By: Emma Phipps


Have you ever looked at rock candy and wondered how it's made? Rock candy is actually a group of large sugar crystals that are "grown" from a sugar-water solution. Sugar, like many other things, can come in many different states. As a solid it can be either be without shape, like when it forms cotton candy or it can be with shape, like when it forms rock candy crystals.


Does Temperature Affect the Growth of Sugar Crystals?


I think that temperature does affect the growth of sugar crystals.

Independent and Dependent Variables

Independent Variable: Temperature of Water

Dependent Variable: Growth of Sugar Crystals


1: Make a sugar-water solution and put it into 6 glasses/jars.

2: Find a warm area, a cold area and a room temperature area, put two jars in each area.

3: Observe the crystals and document the growth every few days. Write what you observe.

4: On day 7, measure the crystals.

Write what you observe.

5: On day 10, take the crystals out and measure them. Write what you observe.

6: Compare the measurements and graph them.

Set Up


  • 6 Glass Jars

  • 6 Wooden Skewers

  • 6 Clothing Pins

  • Sugar

  • Boiling Water

  • Food Dye (Optional)

  • A Cold Area

  • A Hot Area

  • A Room Temperature Area.

  • Ruler

How do sugar crystals form?

Any pure, solid, substance, will form crystals if oversaturated in a solution of water. If you dissolve egg white in water and then let it dry up, it will form crystals (these crystals may be too small to see, but they will be there). Crystals are just the most efficient way for atoms to fit together in a solid, so solids naturally crystallize, given the opportunity.

Day 5

Day 7

Day 10


In conclusion, my hypothesis was proved right. Temperature does affect the growth of sugar crystals. As the graph shows, the crystals placed in cold temperature did not grow at all. The crystals placed in hot grew a little bit faster than the ones placed in room temperature.