# Rate the insulators.

When you go out in the cold, you have no fur to fluff up to insulate yourself. Instead you throw on a sweater, fluffy socks, and other warm clothes. But what materials should you choose? Do this activity to find out.

You'll test socks made of different materials to see which can keep a bottle of warm water warm longest. (If you live in a warm climate, put very cold water in the bottles and see how long it takes to warm up.)

WHAT YOU NEED:

* several (clean, please!) socks made of various materials (try, wool, what else?) * 1 bottle for each sock * for each bottle: cork with hole in center, thermometer * rubber bands * large pot for heating water * funnel

WHAT TO DO:

1. Place one bottle in each sock as shown. (If socks of different materials are different thicknesses, you'll have to find a way to control for thickness. For example, you could use a double layer of thin cotton socks to equal the thickness of wool socks.)

2. Push thermometers through corks and set beside bottles.

3. Heat a large pot of water to 37 [degrees] C (average body temperature).

4. Fill all bottles with heated water, using funnel to avoid wetting socks. Place thermometer and cork in each to seal. (Thermometer bulb should sit in water.)

5. Place bottles outside in the shade and record the temperature of each bottle every two minutes for an hour. (If it's not really cold out, you could use your refrigerator.)

6. Graph how much the temperature drops as time passes for each bottle (material): Plot Temperature on the vertical axis and Time in minutes on the horizontal axis. The better the insulator, the longer it will take for the temperature to drop.

DON'T STOP NOW!

You're still going to sweat in winter. Will the materials you tested insulate as well when wet?

You can find out by repeating the experiment with the same socks - wet. Just before placing bottles outside, immerse each in a bowl of cold tap water to wet sock.

How do your results change? Does one material insulate best under both conditions?

What could you do or add to the sock materials to affect their wet-insulation ability? Try it and see. Design a new sock with maximum insulating ability - wet or dry.