All About Ice Cream

These days if you want an ice cream snack, all you have to do is drive up to the store or flag down an ice cream truck. Thanks to freezers and other technological advances, we can eat ice cream at any time of the year. Making ice cream by hand can help children understand the work that goes into creating this delicious treat.

What you need:
• a clean, empty 3-lb. coffee can
• a clean, empty 1-lb coffee can
• 1 pint of half & half cream
• 1/2 cup sugar
• 1 tsp. vanilla extract (or other liquid flavoring)
• 4 tbsp. rock salt
• ice
• duct tape
• large towel or sheet
• Optional: additional ingredients of your choice, such as cocoa (about 4 tbsp.), slices of frozen fruit, chunks of frozen candy bars, pieces of hard candy, crushed cookie bits, marshmallows, or chopped nuts

What you do:

• Mix the half & half, the sugar, and the vanilla or other liquid flavoring together in the 1-lb coffee can.
• Seal the lid of the 1-lb. coffee can with duct tape. Place this can inside the 3-lb. coffee can. Surround the smaller can with ice and 2 tbsp. rock salt. Seal the lid of the 3-lb. coffee can with duct tape.
• Lay the towel or sheet on the floor. Roll the can back and forth across the towel or sheet for about 10–15 minutes.
• Open the large can and dump out the water and salt. Wipe dry and open the smaller can. Stir the mixture inside well and add in any additional ingredients.
• Reseal the smaller can and repack it in the larger can with more ice and the rest of the rock salt. Reseal the larger can.
• Roll the can back and forth for an additional 10 minutes.
• Open the cans again and enjoy your ice cream!

What you can talk about:

• The key to making ice cream is freezing the cream mixture. Centuries ago, before the invention of refrigeration, people were dependent on naturally occurring snow and ice, sometimes collected from the cold tops of mountains! If the temperature outside was too hot, people could not make ice cream, or “cream ice” as it was called in past times.
• Then people discovered that adding salt to ice lowered the freezing temperature of ice. Ice by itself can only cool the mix to 32ºF, and an ice cream mix must be at a temperature lower than 32ºF to freeze. If you add rock salt to the ice, however, the salt melts the ice and forms a brine solution that drops the temperature to about 8–12ºF and absorbs enough heat to freeze the ice cream on even the hottest summer day.
• Commercial ice cream must go through three important steps while being made: 1.) the ice cream mix is pasteurized, or quickly heated to kill any bad bacteria; 2.) the ice cream mix is homogenized, or forced through tiny valves to break up the blobs of butterfat in the cream and spread them evenly through the ice cream so that they don’t form lumpy clumps; and 3.) the ice cream mix is whipped gently while being frozen. The whipping in the last step mixes air bubbles through the ice cream to make it fluffy. The movement of the whipping also makes sure that as the drops of water in the ice cream freeze, they form many tiny ice crystals, instead of a few large ones that would make the finished ice cream crunchy and icy like a popsicle.