ข้อมูลทรัพยากร

เนื้อหาย่อ : There are millions of different kinds of living things in the world. Some of these things are so small that they can't be seen without a microscope. There may be hundreds of living things in a drop of pond water! Other living things are very large. Some blue whales are more than 30 meters long and weigh over 135 tons. People discover new kinds of plants and animals every year. The world is filled with so many differ- ent living things that no one can be familiar with all of them. But people who study living things try to name them and put them in some kind of order. It is not so easy to find the kind of order that is most useful. Living things are so different from each other in so many ways. But people try to find ways in which they are alike. They study one living thing and try to find what other living things it is most like. The living thing is then classified-put in the group to which it belongs.