According to a new survey, students' safety has become a big problem. Nearly 50% of students say they are worried about robbery on the way to and from school. Now in main big cities in China, some schools have taught an unusual lesson: self-protection. Students like this lesson because there are no exams or boring classes. And they can learn how to save lives and know how to stop danger before it really happens.

      Chen Haoyu, a teacher at Beijing No. 25 Middle School, gives young students advice on how to deal with danger.

★If you are robbed

     Keep calm. lf you can not cry for help or run away. Give the robber your money. Try to remember what the robber looks like and tell the police later.

★If you are in a traffic accident

     If a car hits you. You should remember the car number. If it is a bicycle, try to call your parents before you let the rider go. This is because you don't know how seriously you are hurt

★If it is raining hard and there is lighting

    Don't stay in high places and stay away from trees.

★When there is a fire

    Get away as fast as yon can. Put wet things on your body and try to find an exit. Do not take the lift.

★If someone is drowning

     If you can't swim, don't get into the water. Cry out for help.

      Remember that danger is never as far away as you think. Take care of yourself at all time!

      Our living environment is being polluted faster than before and it seems nobody can prevent it. Time brings us more people, and more people bring us more industry, more cars, larger cities and growing use of man-made materials.

      How can we understand and solve this problem? The fact is that pollution is caused by man —by his desire (欲望）for a modem way of life. So we are often ready to offer everything: clean water, good food, our health and the future of our children. There are more people from the countryside moving into the cities and enjoying the modem society. But as the technological momentum (势头) has grown in the last twenty years, pollution has become a serious problem.

      Now we have to stop to ask ourselves where we are going and why. It makes one think of the story about the airline pilot who told his passengers over the loudspeaker, “I've got some good news and bad news. The good news is that we're going at 530 miles per hour. The bad news is that we're lost and don't know where we are going.” The sad fact is that this problem becomes a true story when speaking of our modem society.

    How much do you know about the bird world?

    Birds use three gaits: walking, running and hopping．

    In walking, the left and the right feet move in turn (轮流)．Each foot is on the ground for more than half the time, so there are more times when both feet are on the ground．In running, each foot is on the ground for less than half the time, and there are more times when both feet are off the ground．In hopping, the feet move almost at the same time．This means that for much of the time both feet are off the ground．

    Middle-sized and large birds walk at low speed and either run or hop at higher speed．Small birds, such as sparrows and swallows, usually do not walk, because walking may be too slow for them．It seems that the more time a bird spends in trees, the more likely it is to hop．Perhaps there is wide space in a tree between one thin branch (树枝) and the next, so walking is not a good choice, while on each small branch there is enough room to set both feet down side by side, so hopping seems to make sense．

    Honey to treat a wound. Eat cherries(樱桃) if someone has a pain in his knee. Your grandmother is probably satisfied with her old-time treatments and now science is catching up with them. Researchers have produced hundreds of studies in the past five years about these grandmothers' old-time home treatments. They are often natural, different from the medicine from the hospitals. Here are some old-time treatments which have been proved（证明） to be useful by the scientists.

    Why do we like drinking water from plastic bottles? Some people think it is healthy and clean. Others drink bottled water because it's easy—you can carry it around with you. In hot countries, like Greece, we often buy bottles of cold water in summer.

    However, making lots of plastic is not a good idea for many reasons. First of all, we need a lot of oil for plastic products. We usually use oil as a source(资源) of energy. If we reduced the number of bottles we made, we wouldn't need so much oil. Plastic bottles also pollute the environment. If we recycled all our plastic bottles, we wouldn't need so much space for rubbish dumps. But in Greece, we don't recycle much of the plastic we use. In 2006, Greeks recycled only about 10% of plastic waste. The rest became rubbish on land and in rivers and seas.

    So next time you want to throw away a plastic bottle in the litter bin, stop and think. If you recycled it, you would help the environment. But what can you do when there isn't a recycling bin near you? Well, there are lots of useful ways that you can use your bottles again. For example, an empty bottle makes a great piggy bank for your pocket money, and if you cut a bottle in half, you will have a plant pot. Go green! You can make a difference.

    There are many colours in nature. But do you know if a colour has weight? I think you'll say "no". But I am afraid you are wrong. If you don't believe, you may do a small experiment.

    First, put two objects with the same weight into two boxes. Then, cover the box. Third, wrap(包裹) one box with a red piece of paper, the other with a white piece of paper. OK. Now hold the boxes with your hand one by one. It is certain that you will think the red one is a little heavier. Why do you think so? A scientist found that different colours have different weight in a man's mind. So he did many tests and at last he got the result. That is to say, every colour has its own weight in our mind and their order(顺序) is the same. The heaviest colour is red, then blue, green, orange, yellow and white.

    The scientist told us that colours also have smell. Can you smell the colour? Of course not. Then why did the scientist say so? That is because every colour stands for a kind of light with a certain wavelength (波长). It reaches our brain(大脑) through sense organs(感觉器官).

    According to this discovery, scientists say that people accept the colours they like, and refuse the colours they hate. So your body and mind will be healthy by using the colors you like. Or you'll be nervous or even get ill. For example, if you stay in a room with red windows, wallpapers and furniture for two hours, you'll feel you have been there for four hours. But if the room is blue, you'll feel you have been there for only an hour. Another example, if a person walks out of a red room and into a blue room, his temperature will fall. That means our body temperature will change with different colours.