Cynthia Pikelis, age 9, of Millinocket, Maine, for her question:

Where does the water go at low tide?

When the high tide rises on your favorite beach, it slops masses of sea water over the land. It creeps up and covers a few inches, then another few inches, of the dry sand. It comes in exactly as far as it should and then it turns back. Inch by inch, all the extra tidal water leaves the sandy beach bare and goes back into the sea. When it gets to low tide, you would think a stupendous amount of water has been added to the sea. Yet the sea seems to be no bigger, no higher than it was at high tide. The truth is, where and when the tide is low, the sea along the coastline actually is lower. Where in the world does all that water go? It piles up in the ocean far away and brings high tides to the beaches somewhere else in the world.

The mighty oceans all link together and cover much more than half of the whole round globe. And they work together as one big ocean to give us the changing tides. Your beach has a high tide and a low tide, then another high and low tide every calendar day. When your tide is high, there are high tides halfway around the globe on the other side. Between the two high tides are low tides. When your tide is low, the ocean water piles up to bring rising tides to faraway beaches.