Frosty Homemade Ice Cream

Use the power of science to make homemade ice cream in a bag! This sweet treat is ready in less than 10 minutes without requiring any special equipment or ingredients. Making homemade ice cream is a tasty addition to our growing list of fun and simple kitchen science experiments.

Reward: Shake Up Gold!

  • One small Ziploc baggie (quart or sandwich size)
  • 1/2 cup of milk (whole milk, but any variety will be fine)
  • 1 spoon of sugar
  • 1/4 spoon of vanilla
  • One gallon-size Ziploc bag
  • 8-10 cups of ice
  • 6 spoon of salt

Once you have all of the supplies ready follow these directions to make this delicious science ice cream in a bag:

Add milk, sugar, and vanilla to the small baggie. Seal the bag, being careful to release excess air.

Add ice and salt to the bigger baggie.

Place the small baggie into the large bag of ice and salt. Seal the large bag. Shake for about 5 minutes or until the milk mixture turns into a soft solid.

CAREFULLY open up the large bag, remove the small bag and rinse it off quickly and thoroughly in cold water (pay special attention to rinse off the opening of the baggie). 

Without this step salt may get into the ice cream, which completely spoils it! 

Either grab a spoon and eat your ice cream right out of the bag, or pour your ice cream into a bowl. Top with sprinkles and toppings of your choice and enjoy!

The Science of Homemade Ice Cream

To make any variety of homemade ice cream, milk needs to be partially frozen. Putting milk directly in the freezer and leaving it there makes the milk freeze solid, which is no good. When you try to eat the ice cream it’s no longer creamy and smooth. It gets all icy and crystal-y and weird.

Water freezes at 32°F, but because milk contains proteins and fat it freezes at a lower temperature. This means that trying to freeze milk with ice cubes won’t work either. You need to add a special ingredient to your ice cubes to make a mixture that is even colder than ice alone. Ready for the secret ingredient? I’ll give you a few clues. It’s white. It’s something almost everyone has in their kitchen. It tastes yummy on popcorn with butter. It’s….SALT!