How Does Your Rock Garden Grow?

With make-them-yourself crystals!



What you need: 

  • rocks and pebbles 
  • ½ cup water 
  • 2 ounces alum (found in canning or spice section of supermarkets) 
  • clear glass bowl

What to do:

  1. Invite your child to gather rocks and pebbles from outside and rinse them in the sink or tub.
  2. Boil the water on the stove. Add the alum and stir until dissolved.
  3. Pour the mixture into a clear glass bowl and fill halfway with rocks and pebbles.
  4. Ask your child what she thinks will happen to the rocks. Will they look the same after a while or will they look different?
  5. Watch the crystals grow! The first crystals should appear after about 30 minutes, but over the next few days additional crystals will appear. 
  6. Encourage your child to keep a record of what the crystals look like each day. She could describe the crystals using words (and measurements), pictures, or both.

Learning Benefits:

  • supports prediction skills 
  • provides practice with observation
Science & Nature Activities
Following Directions
Age 7
Age 6
Age 5
Science Experiments and Projects
Rocks, Soil, Minerals
Outdoor Activities and Recreation