Paper

Nowadays people always use paper to write words, information, drawing etc. But in the past, people didn't have any paper or pens. So they had to use some sticks to write and draw on the floor and ceilings of their caves.

Later on, the Chinese invented paper made from wood pulp. So it meant using up a lot of trees. Some people will not recycle paper after using it and throw it into the rubbish bin. If the trees are all destroyed, we will die because trees give us oxygen and we can't live without it. I think people know about this but they just don't care about it.

Although paper can only be recycled seven times, we should try our best to recycle it.