Fred White, age 10, of Sarasota, Florida, for his question:

Why does the cold make us shiver?

We do not decide to shiver in the cold, or even want to. The body decides to do this, without asking our permission. But when the body does something automati¬cally, on its own, there is usually a good reason for it. Its muscles and all its busy cells need to stay fairly warm. If things get too cold, their complicated operations slow down. There are, of cours, several ways to keep comfortably warm on a cold day. We can turn up the furnace or snuggle into some extra clothes. Exer¬cising the muscles also makes a person warmer.

The body cannot turn up the furnace or add a sweater without permission. But it can order the muscles to get busy and do a little exercising. They get the message and start shaking and shivering. This exercise creates a little warmth, but not much. It is the best the body can do, until you decide to add that extra jacket and enjoy some frisky exercise, such as a merry game.