Learn that salt is a useful chemical to have in the kitchen because it can change the melting/freezing point of water by using it to freeze ice cream.
1/2 cup half & half, 2 tsp vanilla extract, 2 tsp sugar, 1/4 cup kosher salt, ice, gallon-size zipper seal bags, sandwich-size zipper seal bags
You can make ice cream by placing a container of sweetened cream in an ice bath, but it will take a long time to freeze. You can make it freeze much faster by adding salt to the ice.
1. Pour the half & half, vanilla, and sugar into a sandwich-size bag; seal tightly and set aside.
2. Fill a gallon-size bag halfway with ice and add the salt.
3. Place the small bag inside the large bag and seal tightly. Carefully shake the bag until the ice cream is frozen – this should take less than 10 minutes.
Water freezes when the cold molecules line up to form ice crystals. Adding salt to the water disrupts freezing by getting in between the liquid water molecules and the frozen water molecules, making the water freeze at a lower temperature. Not only does this help us make ice cream, but it's also why we put salt on icy roads in the winter. The ice melts because the salt lowers the freezing point of water.