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:
- Invite your child to gather rocks and pebbles from outside and rinse them in the sink or tub.
- Boil the water on the stove. Add the alum and stir until dissolved.
- Pour the mixture into a clear glass bowl and fill halfway with rocks and pebbles.
- Ask your child what she thinks will happen to the rocks. Will they look the same after a while or will they look different?
- Watch the crystals grow! The first crystals should appear after about 30 minutes, but over the next few days additional crystals will appear.
- 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.
- supports prediction skills
- provides practice with observation