Wet and dry
Chemistry · Early Years · The School
Wet or dry
Some things are WET. Some things are DRY. A puddle is wet. A towel out of the wash is wet. Sand at the top of the beach is dry. Sand at the edge of the sea is wet. You can tell by touching it. You can often tell by looking too. Wet things usually look darker.
Some things drink it up
Pour a little water on a paper towel. It soaks straight in. Now pour it on a plastic tray. It sits in a puddle on top. Materials that soak water up are ABSORBENT. Sponges are absorbent. So are cloths, paper and cotton. Plastic, metal and glass are not. That is why we use them to hold water.
Getting dry again
Wet things get dry when the water goes into the air. That is why washing dries on a line. It is why a wet coat dries near a warm radiator. It happens faster when it is warm. It happens faster when it is windy too. The water has not disappeared. It has gone into the air, where we cannot see it.
Put a saucer of water inside a large glass jar. Screw the lid on tight. Put the jar somewhere sunny. Come back a day later. The water in the saucer has dropped. But droplets have appeared on the inside of the glass. Tip them back and you get water again. Nothing could get in or out of the sealed jar. So the water never disappeared. It went into the air. Then it came back on the cold glass.