Tommy Edmonds, age 14, of High Point, N.C., for his question:

WHERE DOES THE WATER GO WHEN THE TIDE GOES OUT?

Tides are like waves. As the earth turns completely around each day, the moon and sun pull on the oceans. At any part of the coast, the water is pulled up in sort of a heap, which is what we call high tide. Then it is pulled away for what we call low tide. When it is high tide in one part of the world, the water has been pulled away from another part.

One scientist gives this good example of where the water goes when the tide is out: Think of water half filling a big pan. Gently turn the pan to the left until the water is almost to the top of the pan. As this happens, the water on the right side becomes very low. Gently turn the pan the other way and the end that had been shallow is now deep. That's how the tides work.