Slushy Experiment
(Also could be a Nutrition Activity)

Materials: Salt, food coloring, Ziploc baggies, cups, fruit and/or vegetable juice 

The night before you want to make a slushy, put half a cup of water and one teaspoon of salt into a plastic bag with a seal. Can add food coloring just to give it a fun look. Squeeze the air out of the bag and roll it into a shape that will fit inside your jar. Put the bag(s) in the freezer overnight. When the bags have frozen put them into a jar with a lid and add a cold liquid. You can use fruit and vegetable juice. Anything with sugar in it will work, but don't pour too much in. Use about 6 ounces of juice for each bag. Start shaking. After a few minutes, you'll see your juice becoming slushy. Pour it into a cup and enjoy!! 

The science part: The salt lowers the freezing point of the water in the bag, so the bag of ice stays colder longer than plain ice. This is what causes the liquid surrounding it to begin to freeze.