On New Year's Day, dedicated swimmers will flock to various northern beaches to make their annual plunge into the icy surf to raise cold, hard cash for local charities. The very thought of it could give you goose bumps — unless you happen to be a penguin or a seal or another animal equipped with a layer of blubber to keep warm. Here's a quick activity that will show your child how well suited these animals are to cope with the cold.

Spoon several large scoops of vegetable shortening into a plastic bag. Have your child pull an empty plastic bag over her hand and insert it into the middle of the shortening in the first bag (this way, her fingers never come into direct contact with the grease).

Now your child should dip the whole ensemble into a bowl of ice water so that her fingers are submerged but the water level stays below the bag tops. Explain that the reason her hand stays comfortably warm is that, like blubber, the shortening helps hold in her body heat.