Homemade bag ice cream is a fun edible science project that kids of all ages will love making as much as they love eating. Make sure to use mittens or a towel so little hands don't get freezer burn! You can also sub your favorite ice cream recipe and simply use the homemade bag ice cream method. (Adapted from Food.com)
In a large bowl or glass measuring cup, mix together the sugar, vanilla extract, and whole milk, until the sugar is completely dissolved.
Fill each gallon zip top bag half full with ice, then add 1/2 cup of salt to each bag of ice. Make sure to use a coarse salt, not table salt.
Divide the ice cream mix between the quart bags, and seal well, pressing the air out as you seal them.
Tuck the ice cream bags into the ice, getting them surrounded by it, then seal the gallon bags, again pressing the air out.
Using mittens or other hand protection, shake the bags for a few minutes. You can periodically feel the inner bag to see if it is freezing.
Once the ice cream mix has frozen, unseal the ice bag and pull out the inner bag. Carefully wipe the inner bag with a towel before opening it so you don't get salt water on your ice cream as you scoop it out.