Theresa Castaneda, age 13, of Gallup, N.M., for her question:

Who exactly invented the wheel?

Archaeologists rate the wheel among the greatest of all human inventions. But nobody can name the inventor or even guess when this genius lived. It seems likely that the wheel was invented many times by widely separated peoples. No doubt they got the idea from watching

and perhaps using rolling logs. In any case, the wheel was used in many different parts of the world before writing was invented, long before the beginning of recorded history.