1 sandwich-size Ziploc bag
1 tennis can/cover ice cubes
1 paper cup of table or rock salt
1 thermometer
2 plastic spoons

Ice cream ingredients
1 cup homogenized milk
2 tablespoons sugar
1/2 teaspoon vanilla
chocolate syrup (optional)

1. Place the ice cream ingredients in the small zip lock bag, seal with as little air as possible and mix well.
2. Place some ice in the can with half of your salt.
3. Place the small bag in the can.
4. Fill to the top with ice, and add the rest of your salt. Record the temperature of the ice and salt before shaking.
5. Shake or roll your can to mix the ice and salt. You may add more ice if needed, but no more salt should be necessary.
6. After four minutes open can and record temperature of ice salt mixture.
7. Continue to mix until ice cream is the desired consistency. (about 5-10 minutes more)
8. Open the can and remove the small bag, rinsing it (the bag) carefully with tap water before opening.
9. Rinse thermometer, open small bag and record temperature of the ice cream mixture.
10. Eat ice cream!
11. VARIATION: This experiment may be varied by using chocolate milk or condensed milk in place of homogenized milk or adding chocolate syrup to the milk.

1. Draw a diagram of the baggie-ice cream freezer. Add arrows to the diagram to indicate the direction of heat transfer (i.e. from the ice cream to the salt mixture or vice versa).
2. How many minutes did it take for your ice cream to freeze?
3. Was the process by which the milk mixture turned into ice cream exothermic or endothermic? Explain, including what was happening to the ice and salt mixture.
4. Is this process a chemical or physical change?