Hooked on Science: Homemade ice cream

It's summer, which means it's hot, which means ice cream. Try your hand at making it at home.

Materials

* 1/2 cup of half and half

* 1 tablespoon sugar

* 1/4 teaspoon vanilla

* 1 zip-top sandwich bag

* 1 gallon zip-top bag

* 3 cups of crushed ice

* 1/3 cup rock salt

Instruction

STEP 1: Place the half and half, sugar and vanilla into the zip-top sandwich bag and seal it.

STEP 2: Place the ice and rock salt into the gallon zip-top bag. Add the sandwich bag into the gallon bag. Seal the gallon bag.

STEP 3: Squeeze the gallon bag until the ice cream thickens.

STEP 4: Remove the sandwich bag from the gallon bag. Open the sandwich bag and taste your homemade ice cream.

Explanation

The salt lowers the freezing point of the ice and creates a cold brine, which absorbs the heat from the bag containing the half and half, sugar and vanilla. This causes the contents in the bag containing the mixture to go from a liquid to a solid, creating homemade ice cream.

Jason Lindsey is a science outreach educator with Hooked on Science. Check out his website hookedonscience.org for webcasts and experiments that might get you hooked on science.