Make Ice Cream in a Bag!

Cool off and have fun while learning how to make ice cream with your kid!
(Note: this recipe makes one serving.)

Colorful ice cream scoops

What to get:  

  • 1 cup (240 mL) half & half or whipping cream
  • 2 tablespoons (30 mL) granulated sugar
  • ½ teaspoon (2.5 mL) vanilla extract 
  • Coarse salt (rock salt or kosher salt)
  • Lots of ice 
  • 1 gallon-size resealable freezer bag 
  • 2 pint-size resealable freezer bags
  • Optional: frozen berries, mini chocolate chips or other flavoring
  • Optional: dish towels or gloves to keep hands warm 

What You Do: 

  1. Combine sugar, vanilla, half & half, and any desired flavorings in one of the small bags. Push out excess air and seal tightly. Place this bag into the other small bag, squeeze out the air, and seal tightly.
  2. Put 6–7 cups of ice and 1 cup of coarse salt into the large bag.
  3. Put the small bag into the large bag and seal tightly.
  4. Shake the bag of ice vigorously for 7 to 10 minutes, until the ice cream has hardened to your preferred thickness. You may need to add more ice if the ice in your bag melts while shaking.
  5. Remove the bag of ice cream and rinse the outer bag quickly under cold water to remove the salt. Then open the inner bag and enjoy your homemade ice cream!

The science behind the experiment:  

Plain water freezes at 32°F (0°C), but we can lower that temperature by adding salt to the water. Heat is gradually transferred from the warmer substance to the colder, melting the ice and chilling the ice cream ingredients. Increasing the concentration of salt lowers the melting temperature and reduces the amount of time you have to shake the bag. Shaking the bag not only mixes the cream, sugar, and vanilla together, it also breaks up the ice crystals as they form and incorporates air into the mixture. Smaller crystals means creamier ice cream!

Scientists ask questions:

  1. What would happen if you just buried the bag of ingredients in the ice and didn’t shake it?
  2. Can you make ice cream without adding salt to lower the temperature?
  3. What if you don’t have coarse salt? Can you use table salt instead? Do some online research to learn more.

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