Wendy Smith, age 10, of Schenectady, New York, for her question:

What makes a rattlesnake's tail rattle?   

 This is the beware of rattlesnakes season. They are waking from their winter hibernation and even the youngsters are deadly dangerous. At least one species lives in every state. So let's first raid our libraries for books with clear pictures of the monsters we are likely to meet in our own neighborhoods. However, very often we hear a rattler before we see him. So we also need to know what he sounds like. Sometimes we get a chance to hear his rattle on a TV show. It is the sort of noise you could make by rattling together very stiff leaves with small, very dry bones.     Actually, the rattler's rattle is a row of bony little buttons at the end of his tail. He shakes or vibrates them when he is nervous or ready to strike. This is the time to stop asking questions and run, don't walk, in the opposite direction. If you move as fast as you should, he can't possibly catch you. Also scoot away if you happen to see and recognize him, even if he doesn't buzz his rattles.