Science Project: Homemade Ice Cream in a Bag

It’s currently a high of 113 degrees here in Los Angeles, beginning an #LAHeatwave – A far cry from our usually perfect 75-degree days.

“So what do we want?”


“And when do we want it?”

“NOW!” cry my kiddos.

I don’t respond well to demands, so I decided we would make the ice cream ourselves, which then obviously turned into a learning opportunity by way of a science experiment – naturally!

Perhaps I wasn’t the only one who thought to make ice cream on this 113-degree day, since my local stores were all out of rock salt (even Amazon!). However, my good friend Google informed me that coarse Kosher salt was a suitable alternative since it has large granules similar to rock salt, and is less processed. The drawback? It costs almost double that of rock salt.

Here’s why the salt is important: When you add salt to the ice, it allows the ice to get colder (lowering the freezing point) and therefore, allows your ice cream to form and harden quickly. Rock salt is ideal because it is larger, less processed ‘rocks’ that are not used for cooking, and therefore less expensive.

What You’ll Need:

  • 1 Cup Half and Half (or 1/2 cup milk and 1/2 cup heavy cream)
  • 2 Tablespoons sugar
  • 1/2 teaspoon vanilla extract
  • 3 Cups Ice, crushed
  • 1/3 cup rock salt or coarse kosher salt
  • 1 sandwich/quart sized plastic sealing bag (ziploc)
  • 1 gallon sized plastic bag (ziploc)
  • chocolate syrup (optional)


  • Add half and half, sugar, and vanilla to the sandwich/quart sized plastic sealing bag. If you prefer chocolate ice cream, add in two tablespoons of chocolate syrup. To help stabilize the bag for my younger son, I put the bag in a measuring cup while he added his ingredients.
  • Seal, making sure to remove as much air as possible. Knead it to mix the ingredients.
  • Add ice and salt to your larger plastic bag. No need to stir!
  • Place your smaller bag with your half and half mixture inside the larger ice bag, seal.
  • Your ice cream should harden and be ready in about 5-10mins. The more you shake, the sooner it is ready! Since my younger son added the chocolate syrup to the mix, it took a little longer to set than the vanilla that my daughter made, but he was still thrilled with the results! (so much so that he wanted to eat it right out of the bag!)

This wonderful, quick, and educational treat really hit the spot today! Next time, we’ll have to try mixing in some chocolate chips m&m’s, or ???

Give it a try and let us know what you think in the comments below!

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