Grow Your Own Rock Candy

Have a junior gemologist who loves rocks? Teach the science behind crystal formation with a sweet twist by growing rock candy at home. It’s a science experiment your child can eat! Rock candy takes a few weeks to grow, so make sure your child plans ahead.

Recipe:

Rock Candy Lab from Kids Cooking

Prep time: 15 minutes

Wait time: 2-3 weeks

You will need:

• ½ cup water
• 1 cup sugar
• Food coloring (optional)
• Tall glass jar
• Saucepan
• Whisk
• Cotton String
• Chopstick or popsicle stick
• Scissors

Instructions:

1. Have your child cut a piece of string 2 or 3 times the height of your jar. Tie one end of the string to the chopstick. *TIP: Cut 3 pieces of string and braid them together to make bigger rock candy crystals. Set aside. 

2. PARENTS DO THIS STEP! Put the water into the saucepan and bring it to a boil on the stove.

3. PARENTS DO THIS STEP!  Turn off the heat and immediately add sugar to the saucepan. Whisk for 2 minutes until the sugar is dissolved. The liquid should be clear, but if you’d like, you can add a drop of food coloring now.

4. PARENTS DO THIS STEP! Carefully pour the mixture into the tall jar. 

5. Ask your child to dip the string into cold water and roll it in loose sugar to “seed” the crystals. 

6. Then, have your child lay the chopstick across the mouth of the jar with the string dipped inside. The dangling end can coil around the bottom of the jar.

7. Have your child leave the jar on the counter for 2–3 weeks to let the candy crystals grow. Your child can lift the string out of the jar every few days to check on it, but make sure to put it back in the sugar mixture. When your child is happy with the number of crystals that have grown on the string, remove it, and hang it up to dry.

8. Enjoy!

How it works (the science part)

Two things are required to grow crystals: seed crystals and a saturated solution. The sugar granules your child rolled on the string are the seed crystals. The sugar water your child poured into the jar is a saturated solution. (This just means that if your child added any more sugar to the water, it can’t dissolve.) As the saturated solution cools and evaporates, crystals will grow on the seed crystals and get bigger and bigger to give your child rock candy!