2 Ziploc sandwich bags
1 Ziploc gallon bag
Chocolate syrup (or vanilla flavoring and about a tablespoon of sugar)
Salt (Ice cream salt or rock salt works best, but table salt works, too.)
Heavy whipping cream
Ice cubes
Fill a sandwich-sized Ziploc bag with 1/2 cup of cream and some chocolate syrup (or vanilla flavoring and a a little bit of sugar, if your child prefers vanilla ice cream). Seal the bag tightly. Place that bag inside another sandwich bag and place the double bagged mixture inside a gallon bag. Fill the gallon bag with lots and lots of ice. Then add more ice. Add 1/4 cup salt to the ice. Seal the gallon Ziploc bag and place it into a plastic grocery bag. The bag gets very cold, so the grocery bag will really help!