Observations and results
When you dunked your fingers in the ice-cold water, did the finger covered in shortening stay warm longer than the finger that was not covered? Was there not as large a time difference when you put your fingers in the warm water?
Mammals that have adapted to live in cold waters—such as polar bears and whales—can stay warm largely because of their blubber, a thick layer of blubber. The blubber is evenly spread over much of their body, just as the shortening in this activity covered the surface of your finger in a thick layer. Since adipose tissue has a relatively low thermal conductivity, it does not transfer heat well compared to other tissues and materials. Humans have developed some insulating materials for our own daily use. For example, Styrofoam is another material that does not conduct heat relatively well, whereas metals conduct heat very well. This is why hot drinks are often served in Styrofoam, since it keeps the heat inside the cup, thus preventing your hands from being burned. (For the same reason, it can also keep cold drinks cool longer than, for example, a paper cup.) What other materials can you think of that work as insulators?
More to explore
Sink or Swim: Muscle versus Fat from Scientific American
Blubber from National Geographic Education
Is Muscle a Better Insulator than Fat in Cold and Heat? from MadSci
What Are You Blubbering About? from Science Buddies
This activity brought to you in partnership with Science Buddies