week 18: make some ice cream!

The weather is warming up. Make some tasty ice cream using science and a couple of common grocery items!

Materials: 

• Plastic zip bags: 1 gallon-size and 1 quart-size
• Ice 
• Salt of any kind
• Sugar
• Vanilla extract
• Half & half / milk / heavy whipping cream

Directions:

1. Add about 3-4 cups of ice and 1/3 cup salt in the larger gallon bag.
2. In the quart bag, add about 1 tablespoon of sugar, a quarter teaspoon of vanilla extract, and half a cup of half & half. 
3. Seal the quart bag and insert it inside the larger gallon bag. Make sure both bags are sealed tightly.
4. Shake the gallon bag vigorously for about 5 minutes. You may have to use a towel or gloves to hold the bag if it gets too cold to touch.​
5. Remove the quart bag from the gallon bag and empty its contents into a bowl, or enjoy your ice cream straight from the bag! We added some toppings to ours!

What's Going On?
The salt is the key ingredient here. Although you don't want salt inside your ice cream, it is crucial that it's outside it in this project! The salt, when mixed with the ice in the gallon bag, made the temperature of the outside much colder than what it would have been with just the ice. This decrease in temperature is what allowed the liquid mixture in the quart bag to turn into solid ice cream. Try the experiment again with different variations! You can substitute the heavy cream for another type of milk, or add less or no ice to see what happens.

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