Why Do My Ice Skates Slide over the Ice so Easily?
Why Do My Ice Skates Slide over the Ice so Easily? When you ice-skate, you are not skating on the ice itself, but on a slippery film of water between the ice and the...
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What Makes Waves in the Ocean?
What Makes Waves in the Ocean? Most waves in the ocean are caused by the wind. Somewhere, far out at sea, wind ruffles the surface of the water. Ripples form and grow...
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What Are the Dark Spots on the Moon?
The dark spots we see on the moon are really the moon’s large flat plains. The moon’s rugged surface is covered with mountains, craters, and great lava...
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What Is a Sponge?
A sponge is an extremely simple kind of water animal with a soft, elastic skeleton. It has no head, mouth, or brain. Sponges hatch from eggs. The baby sponge attaches...
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Why Is the Ocean Salty?
Why Is the Ocean Salty? The salt in the ocean comes from the earth’s crust. Since the very beginning of the earth’s history, water on its surface has been...
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