Here's a fun treat for a hot day!
How can you bake ice cream? Well, if you insulated the ice cream well enough, it can withstand the heat of the oven. An insulator is a weak conductor of heat energy. In this activity, you'll see an insulator in action - and end up with a tasty treat.
What You Will Need:
- Cookies
- Ice Cream (very frozen)
- 3 Egg Whites
- 1 cup Granulated Sugar
- 1/4 teaspoon Cream of Tartar
- 1/4 teaspoon Salt
- 1/2 teaspoon Vanilla Extract
- Mixing Bowl
- Electric Mixer
- Cookie Sheet
- Spoon
- Oven
What You Do:
- Beat egg whites in a bowl with an electric mixer.
- Add Cream of Tartar, salt, and vanilla - then whisk the mixture until it stands up in stiff peaks.
- Slowly add sugar by sprinkling a tablespoon at a time over the mixture. Combine and beat until the meringue mixture is smooth and glossy. You will need to repeat this process for each cookie you want to make
Don't overbeat or the mixture will become to runny. - Preheat oven to 450 degrees Fahrenheit.
- Put your cookies on a cookie sheet, then place one firm scoop of ice cream onto each cookie. Top the ice cream and the cookie with the whipped egg whites. Make sure the ice cream is completely covered by the meringue.
- Bake the ice cream for 3 to 5 minutes, then remove the cookie sheet from the oven when the egg whites get slightly browned.
- Cool slightly, then enjoy!
The Science:
Notice how the cookie got warm, but most of the ice cream remained frozen? That's because the egg whites and cookie form a layer of insulation that prevents the heat from penetrating to the ice cream.
Cream of Tartar is an acid. When it becomes moist, it releases carbon dioxide, which helps to aerate the meringue. When egg whites are beaten, they too make small air spaces. Both the air and the carbon dioxide are trapped in the beaten egg whites, and they act as an insulator. As the sugar hardens, it too acts as an insulator. When the meringue is spread over the ice cream, the ice cream is insulated. The heat of the oven cannot get in during the baking, so the insulation lets the meringue cook without melting the ice cream. Cool, eh?!
