Billy Smith, age 10 of Tuscon, Arizona for his question:

Where do the frogs come from when it rains?

Sometimes after a summer shower, the giro and seems to be alive with hopping frogs. Plop, plop    they merrily spring up and down in the wet grass and over stony ground. Where did they come from and where were they before the rain? This mystery has puzzled people for a 1ong time .

Some thought that the sudden swarm of frogs must come down with the tumbling rain. They explained that the frogs were first drawn up there by the sun as it evaporated water from the streams and ponds. But, since the sun can only evaporate water in tiny molecules of vapor, this cannot be true. What's more    any little frog who had fallen from a rain cloud would be in no shape to hop merrily among the grass and stones.

The best way to solve the mystery is by studying the habits of the little frogs themselves. This would be a big job if we had to study all of them, for there are over 200 different kinds of frog in the world    17 different kinds live in America. All are amphibians, living a double life    part in the water and part on land. All begin life as eggs in the water and live through a fishy tadpole stage.

Their differences begin to show when the frogs are grown up. Some kinds have strong, webbed feet and live their lives forever in and out of the water. Some smallish frogs have disc suckers on their toes and when full grown take up life as tree dwellers. Others have large outer toes which they use for burrowing holes in the ground. Certain of these land dwelling frogs never go near the water after their tadpole stage except to lay more eggs or more tadpoles.

All frogs are cold blooded creatures. They depend upon the air around them to keep them comfortably cool or warm. Many of the stream dwellers sleep through the cold winter in a cozy hole in a bank or stream bed.

In the hot, dry days of Arizona, the little land dwelling frogs scoop themselves holes and small caves below the scorching ground. There they escape the heat of the summer days, hidden below the cooler undersides of stones, cozily buried under the damp roots of sheltering trees and even cactuses.

The damp air from a sudden shower will tingle the skins of the drowsy frogs and awaken them to activity. Here they come, one after an other    plop, plopping all over the place. They will hop happily about, catching themselves an occasional fly, until after the shower is over. Then the sun comes out and dries up the summer air again, the merry little hoppers will all go back to their shelters and doze until the weather suits them again.