Insulating your house holds heat in, so you run your furnace less often when it's cold outside. However, insulation can also keep things cold -- your refrigerator, for example, is insulated to keep the heat out. Either way, insulation saves energy by keeping your appliances from having to work as hard to maintain the temperature. This experiment helps you find out which materials make the best insulators.
Start with two cardboard shoe boxes. Tape black paper to the outside of the bottom of each. Place the top of each box upside down in a sunny location. Lay a thermometer on each top.
Now, fit the bottom of one box over the top so that the black paper faces up toward the sun. This uninsulated box is your control. It shows what happens without insulation.
Next, take the material you want to test, shape it to completely fill the bottom of the second box and tape it to make sure it stays in place. You can choose almost any material to test, including Styrofoam, a towel, layers of newspaper, a piece of bubble wrap or some artificial fleece. Fit the box over the other top. Make sure the two boxes receive the same amount of sunlight.
After 15 minutes, open the boxes and record the temperature in each. The inside of the insulated box should be cooler than the control box. The greater the temperature difference, the better the material works as an insulator. Repeat the experiment with different materials. Finally, think about why some materials insulate better. For example, maybe they trap dead air spaces that don't allow heat to circulate [source: Energy Information Administration: Insulation].