Frosty Salt Can Magic

What you need

• Empty clean metal can, 1
• Ice cubes, enough crushed ice to fill the can about two thirds
• Salt, 3 large spoonfuls
• Spoon, 1
• Plate or tray, 1
• Second metal can, for plain ice, 1 (optional)

How to do it

Grown-up prep: Open and empty one or two metal cans, rinse them, and check that the rims are smooth. Have crushed ice and salt ready on a tray.

1. A grown-up opens the can and checks the rim for sharp edges. A grown-up does this
2. Fill the can about two thirds full with crushed ice.
3. Fill the second can with plain ice, but no salt.
4. Add three big spoonfuls of salt to the first can.
   Ask: What do you think the salt will do to the ice?
5. Stir the ice and salt for about 30 seconds.
6. Wait five minutes and keep watching the outside of both cans.
   Ask: Which can do you think will change more, and how?
7. Spot the tiny water droplets, then the white frost appearing.
8. Gently touch the frost with one fingertip.
9. Show someone your frosty can! Can you make even thicker frost next time?
   Ask: Where do you think the water on the can came from?

Play it again

• Salt race: try different amounts of salt in two cans and see which frosts first.
• Frost art: draw a picture in the frost with a cotton swab before it melts.
• Humid test: try it in a steamy bathroom and a dry room and compare the frost.