Make Your Own Ice Cream

Sep 21, 2020

One way to beat the heat is to treat yourself to a sweet ice cream treat every once-in-a-while. Making ice cream at home is an easy process that requires you to apply many STEM principles. So, let’s make some delicious ice cream in today’s STEM Play of the Day from the Ripken Playbook.


  • 1 – small zipper plastic bag (sandwich size ideal)
  • 1 – large zipper plastic bag (gallon size ideal, but as long as its larger than the small bag)
  • 1 cup of milk or heavy whipping cream
  • 2 tsp granulated sugar
  • ½ tsp vanilla extract
  • Several cups of ice
  • ½ cup salt (table salt will work fine, but kosher or rock salt are also acceptable)


  1. In the small plastic bag, add the 1 cup of milk or cream, the 2 tsp granulated sugar, and ½ tsp vanilla extract. Press out the excess air and seal the bag. Make sure it is closed tight so the liquid does not leak out. You can place this bag inside a second small bag to further prevent leaks.
  2. In the large bag, add the ice to fill the bag about halfway, and then add the salt.
  3. Place the small bag inside the large bag with ice and salt, and then seal the large bag. 
  4. Shake the bag for 7-10 minutes, or until the ingredients in the small bag reach the consistency of ice cream. You can flip the bag, shake it, twist it – as long as the ice is moving around the smaller bag allowing for it to reach freezing temperature. You may want a towel or oven mitts to hold the bag as it does get quite cold! Be sure to feel the smaller bag a few times while mixing to check if it is ready. 
  5. Once it reaches your desired consistency, take out the smaller bag, add any toppings you desire, and enjoy your homemade ice cream! 


  • Why do you think we add salt to the ice? 
    • Salt is added to the ice to allow it to get colder than the freezing temperature of water. This is necessary for making ice cream because milk freezes at a lower temperature than water.  
  • Can you think of any other times you’ve seen salt used to change the temperature things freeze?
    • Think of roads in the wintertime – salt and brines are used so that wet roads can get colder than 32 degrees Fahrenheit 
  • How did the ingredients change throughout the process? What changes did you observe in the milk mixture?
  • What do you think would change if you used a different type of milk?
    • The consistency would be different due to the varying fat content in types of milk. Heavy whipping cream will create a creamier ice cream whereas skim milk will not taste as creamy due to the lack of fat. While the heavy whipping cream may be more palatable, it is also not as healthy, so there are tradeoffs for each type of milk. 

Share a photo of your homemade ice cream with us on social media!