Combine the ice and salt in the gallon bag.
Combine the milk, sugar, and vanilla extract and pour into the pint bag.
Seal the pint bag (double check it!) and place it inside of the gallon bag with the ice and salt.
Shake the gallon bag for about five minutes, or until the ice cream mixture is frozen.
Open up the gallon bag and take the pint bag from inside.
Grab a spoon, you just made ice cream (with science).
Hmm... it seems nobody's added a conclusion for this experiment yet. You can suggest one here.