Keep It Cool!

Invite your child to dip one fingertip into some water that is at room temperature, then hold it up with the rest of the fingers on one hand. Ask, "How does the wet fingertip feel compared with your other fingertips? (Answer may be: Cooler.) Say, "Wave the wet fingertip. How does that feel?” (Even cooler.)

Explain that our bodies have built-in coolers. Our sweat cools our bodies as the water in it evaporates from our skin. Ask your child, "Do you think we can use the evaporation of water to keep a chocolate-covered candy cool so it doesn’t melt?"

Review how your child will do the experiment. Keeping the candies in their foil wrappers, your child should wrap one in a dry paper towel and the other in a wet paper towel. (To wet it, dip it into the water and wring it out.)

Optional: Have your child wrap the bulb end of a thermometer against each patty using the dry and wet paper towels. Note the temperature on each before placing under the lamp.

Your child should then place the candies side-by-side under the lamp and bend the lamp down until the bulb is 1-2 inches from the candy. Using the timer, she will time her patties for ten minutes and then check to see what happened.

After ten minutes, have your child remove the paper towels, open the wrappers, and compare what happened to the candies under the different conditions (wet vs. dry). If using thermometers, have her also note the temperatures on both thermometers after ten minutes.

Discuss what your child observed. Ask, "How did the candies compare when you opened them?” (The dry one was more melted than the wet one.) If she used thermometers, ask her to describe the difference in the temperature at the end of the experiment.

Ask your child if she can now think of new ways to cool down on a hot day. For example, she could wrap a wet cloth around her neck or forehead.