Our skin is like a bag that we live in. Inside the bag our bodies are mostly water. Our water is like the water in the sea. It is very salty. Also, like the ocean, we can lose our water. The wind and the sun could take it away. Our bag of skin keeps our body's ocean from drying up.
Our skin keeps out sunshine. Too much sun can hurt us. Skin also protects (保护) us from the dirt. That's important because some kinds of dirt is not good for our health. Our skin feels things. It feels warm things, cold things, things it touches, and things that hurt (伤害) it. A campfire (篝火) feels warm. A snowball thrown in our face feels cold and hurts. A hug is the touch of another person's skin on our own.
Our nails are like very hard skin. They help keep our fingers and toes from getting hurt. Our nails aren't as strong or sharp as the nails that animals have. But they are good for scratching back sand picking up coins.
