Mixing fun with science yields creamy delicious treats

Keep summer fun alive by making homemade ice cream. I remember using my grandparents’ handed-down manual ice cream maker with the rock salt and cranking until our arms ached, but it was so worth all the hard work! Technology has made the process easier with electric or simple freezer models now available, but did you know you can make ice cream in a resealable bag in just 10 minutes?! Give this idea a try for a fast, simple science experiment with a creamy delicious ending.

Vanilla ice cream in a bag
  • ½ cup half-and-half
  • 1 tablespoon white sugar
  • ¼ teaspoon vanilla extract
  • 4 cup ice cubes, or as needed
  • ½ cup kosher, rock or table salt
  • 1 gallon-size resealable bag
  • 1 pint-size resealable bag

Step 1: Combine half-and-half, sugar and vanilla extract in a pint-size resealable plastic bag; seal tightly!

Step 2: Put ice, salt and the tightly sealed bag containing the cream mixture into a gallon-size resealable plastic bag and seal tightly.

Step 3: Wrap the big bag in a kitchen towel to protect hands from the cold and gently shake the bag for 5–10 minutes until contents thicken into ice cream. Wipe salt from the top of the pint-size bag before opening to prevent salt from getting into the ice cream.

To make different flavors, mix in chopped fresh fruit like strawberries with the liquid ice cream mixture. Don’t forget to add toppings like chocolate chips or crushed cookies if desired and let the kids scoop it right out of the bag for fun. Trish O’Neill, founder and owner of The Cooking Studio in Fort Collins, also recommended their popular Coconut Lime Sorbet recipe for families (see sidebar), saying “With only three ingredients, anyone can make it and it’s very fresh and tangy, and no dairy makes it a lighter dessert.”

If you would like to focus more on the science of the activity, see the following ideas.

  • Vary the recipe/process as follows: In Step 2, leave out the salt to see what happens. Try using heavy whipping cream or milk in place of half-and-half.
  • Take the temperature of the ingredients throughout the process.
  • Questions to ask: How are the ingredients changing during this process? What role does the salt play in the process?

Official lab worksheets can also be found for a few dollars at www.teacherspayteachers.com/Product/Ice-Cream-in-a-Bag-Science-Lab-Worksheets.

Coconut Lime Sorbet

courtesy of The Cooking Studio, Fort Collins

Servings: 1 quart


One 8 oz. can cream de coco (ie: Coco Lopez cream of coconut)

One 15 oz. can coconut milk

8–10 limes


1. Juice the limes and put the lime juice in a bowl—set aside (if limes are small use 10, if they’re medium/large use 8)

2. Whisk together the cream de coco and coconut milk and then add the lime juice and mix until well combined

3. Get the frozen churning-bucket from the freezer and put the ice cream base into it, put it in the churner and put the whole thing into the machine. Turn it on and leave it churning until a soft sorbet is formed. Put into the freezer for an hour or overnight.