Grow Rock Candy Crystals: A Sweet & Fun Science Experiment

Grow Rock Candy Crystals

Have fun with your kids learning about geology and making a sweet treat, too! Grow rock candy crystals like a pro with our easy experiment instructions. Rock Candy is like an igneous rock. The process begins by melting sugar in boiling water creating a solution, much like the magma inside a volcano. As the water sits and cools, it forms crystals much like cooling magma forms crystals of a rock. For added fun, try coloring your “magma” solution for an exciting and tasty final rock!

SAFETY FIRST!  Please get an adult to help boil and handle the water and scissors.  Do not spill sugar on the burner as it can cause a flame.

Ingredients for your Rock Candy:

  • Clean Glass Jar
  • Cotton String
  • Scissors
  • Pencil
  • 1-2 Cups boiling water (have an adult help boil the water)
  • 2-4 Cups white sugar (use approximately twice as much sugar as water)
  • Saucepan
  • Stirring spoon
  • Tissue
  •  Notebook
  • Tape (optional)
  • Camera (optional)

How to Grow Rock Candy Crystals:

Step 1:  Have an adult place the water in a saucepan and heat over medium.  Sugar will dissolve better if the water is boiling or almost boiling.  Stir sugar into the water ¼ C at a time.  Completely dissolve the sugar into the water following each addition.  You will know that the sugar is dissolved if the solution is clear and no crystals remain.  If you see sugar crystals in the bottom of your pan that will not dissolve, you have saturated your water.  Set the pan aside to cool while you prepare the jar and string.

Step 2:  Tie a piece of string to a pencil and hang the string in the glass jar.  If your string is not rough, have an adult fray the string slightly with scissors.  Rest the pencil across the top of your jar and tape it in place if necessary.  Make sure that the string does not touch the bottom or sides of the jar.

Step 3:  Once the sugar solution has cooled for 10-15 minutes pour the solution into the glass jar.  Cover lightly with a tissue and place the jar in a cool location out of the way.

Step 4:  Leave the string in place overnight for small crystals.  Leave the string in place for several days or weeks to grow large crystals.  Sugar crystals grow best in a cool location with low humidity.  Do not move the jar or remove the string often because it can slow the crystal growth. To grow the largest crystals, replace the sugar solution every few days.

Check the growth of your crystal candy periodically.  Document your experiment in your notebook daily with notes, drawings, and/or photos.  We would love to see photos of your crystals!

4 Responses to “Grow Rock Candy Crystals: A Sweet & Fun Science Experiment”

  1. gr8t it is so mad and wonderful and awesome and funkadelic

  2. good job

  3. cooooooooooooooooooooooooooooooooooooooooooooooooooool!


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