DIY Ice Cream

Cool Science, Quick Crafts


to turn your liquid cream into ice cream, you need the stuff around it (in the big bag) to get colder than the ice that will form in the cream in the little bag. how do you do it?

Salt changes the freezing and boiling temperatures for water by a tiny bit. When you add salt to the ice cubes, it causes them to melt faster (like using salt on an icy sidewalk) but the melted salt water is actually *colder* than regular ice. The colder-than-ice mixture slushes around the ingredients, freezing the cream into ice cream… mmmm… delicious!

As long as there are still a few ice cubes in the bag, you know that the slushy water is still colder than the ice forming inside the cream

1 hour

maker checklist

  • 4 to 6 cups of ice
  • 6 tablespoons kosher/rock salt
  • 1 tablespoon sugar
  • 1/2 cup half-and-half
  • 1/2 teaspoon vanilla extract
  • pint-sized Ziploc bag
  • galloon-sized Ziploc bag



fill your large Ziploc about half-full with ice; add the salt and shake it up until it’s evenly coated; set aside.


combine half-and-half, sugar, extract and pinch of salt in the small bag; then seal it tight, making sure there are no gaps!


nestle the small bag of ice-cream mixture into the large bag of ice so that the ice surrounds it. seal it up and shake it up!