First the sky turns dark. Then round raindrops start to fall. Big drops plop on the sidewalk. Soon, these big drops have turned into something new. They form a big puddle! Puddles are a lot of fun to splash in. But just like the rain, these puddles don't last forever. Once it stops raining, where do puddles go? They disappear. Heat from the sun warms the puddles just like it warms all of the water on the earth. The water in a puddle soon turns into water .....