Richard Gipko, age 12, of Bedford Heights, Ohio, for his question:

How does a bat fly?

The bat is the only mammal animal that flies like a bird. And a bird, of course, flies by flapping his wings. Both birds and bats have wings instead of arms but their wings are not exactly alike. We have to examine the bones inside to show that a bird's wing is a modified arm, or fore limb. This modification can be seen quite plainly in the wing of a hat. He has claws and finger bones. The hand and arm bones support a wing of leathery skin, which is covered with very thin fur.

As a bat beats his wings, he packs the air into invisible cushions. He creates drafts and currents and pockets of air that are denser that the air around. These eddies and pockets of air work together to keep his little body froth falling and at the same time push him forward. These airy dynamics keep him flying only as long as his beating wings keep creating them. If he stops flapping, down he falls.