There are about forty-seven different kinds of kangaroos(袋鼠) in the world. The smallest are about a fourth of a meter long; the biggest are taller than a man. Kangaroos have very long strong back legs. These are for jumping. They also have long strong tails(尾巴) to rest on. Kangaroos’ front legs are much shorter, and are almost like arms. Kangaroos’ heads are quite small, but their ears are quite large.Mother kangaroos have a pocket at the front. They have one baby each year. When the baby is born, it is straight into its mother’s pocket. The baby kangaroos stay there for six months.The biggest kangaroos stand more than two meters tall, and their legs are so strong that they can jump more than nine meters. They are very fast, and can travel at more than 50 kilometers an hour. They are very strong, but they only eat fruit, leaves and grass.

We have been learning about the brain at school this week. The brain controls every part of the body. But not only people have brains, animals have brains too.

Of course, animal brains are not as big as ours. My dog, Benny, is very clever. He will come to you if you call his name, and he can even pick up the phone and bring it to you. But he cannot talk, write or use a computer, like you and me.

A dog’s brain weighs only 72 grams, so it is not very big at all. A normal (正常的) human brain weighs about 1,400 grams and it is much bigger. Because a person’s brain is heavier and bigger than a dog’s brain, a dog cannot do as many things as a person can do.

Cats have even smaller brains, a cat’s brain weighs around 30 grams. Fish’s brains are really small. This is why they do not have very good memories.

The dolphin has the biggest brain in the animal world. Dolphins’ brains weigh around 1,700 grams. Many people think dolphins are very clever.

If we did not have brains, we would be just like trees. We would not be able to move, talk or play games. The brain is the most important part of the body.

Do you know some animals can talk? Yes, dolphins (海豚) can talk. They talk with sound (声音). Dolphins travel in a group (群). We call a group of fish “school”. In the special school, dolphins travel in the water. Dolphins are mammals (哺乳动物), not fish, but they swim under the water.

Dolphins talk in the school. They talk when they are happy or sad. They say “welcome” when a dolphin comes back to the school. They talk when they play. Some people catch dolphins for the Ocean (海洋) Parks. And people go to watch the dolphin show. But dolphins don’t like to be away from their school. In the Ocean Parks, they feel unhappy.

Dolphins and people are good friends. There are many stories about them. They often help people. Sometimes they save people. We hope dolphins can live in their school.