Ice Cream in a Bag!

Question to Explore:

How can we use chemistry to make ice cream?


  • 1/2 cup half and half
  • ¼ tsp vanilla
  • 1 TBSP sugar
  • 3 cups ice
  • ⅓ cup kosher or rock salt
  • Gallon size ziploc bag
  • Quart size ziploc bag
  • Sprinkles, chocolate sauce, or fruit for flavor


  1. Pour the ice and salt into a gallon size bag.
  2. In a quart size Ziploc bag, mix half and half, vanilla, and sugar together. Seal the bag.
  3. Place the quart size bag into the gallon size bag.  Shake the bags for approximately five minutes until your milk becomes solid.  (Use gloves while shaking because the bag will get very cold.)

More Ice Cream Experiment Questions to Explore:

  • What happens if you don’t use salt? Compare two ice cream bags (one with salt and one without)
  • What happens if you use a different type of salt? Compare multiple kinds of salt and test which makes the best ice cream!
  • What happens if you try another type of milk? (almond milk, soy milk, etc.)


The salt and ice are the key!  In order to make homemade ice cream, your ingredients need to freeze.  When the salt and ice mix together, it creates a solution.  Salt lowers the temperature at which water freezes.  As you shake the bag, your ice begins to melt and the ingredients inside the smaller bag start to freeze. The cold is transferred to the cream mixture.  The shaking also mixes air in the ice cream mixture causing it to become fluffier.

Creating homemade ice cream also explores changes in the state of matter.  The ice cream mixture starts out as a liquid, but changes to a solid in it’s frozen form.  However, it can also turn back to a liquid when it melts, thus creating a reversible physical change.

Still Curious?

Check out these resources!

Watch the following video of the Sci Guys making ice cream in a bag!


Photos: https://www.sciencebuddies.org/stem-activities/ice-cream-bag

Featured photo: https://www.delish.com/cooking/recipe-ideas/recipes/a54721/ice-cream-in-a-bag-recipe/