Today there are many fires than in the past. Over 100,000 wildfires burn each year in America. Russia has 20,000 to 35,000 wildfires every year. Australia has on average 60,000 each year. These fires destroy（损害）huge areas of forests and burn hundreds of homes.

Many experts believe there are several reasons for this sudden increase in fires. The first reason is climate（气候）change. Recent weather has been warmer and drier. This leads to dangerous fire conditions. When lightening strikes（发生雷电），dry grass easily catches fire. Hot winds add to the problem. The wind spreads a fire quickly. In 2010, Russia had the hottest and driest summer in a century. In just one month, 500 fires destroyed over 2,000 homes. Some people lost their lives.

Traditional fire-fighting practices are another reason for the increase in fires. In America, firefighters used to quickly put out every fire. They didn't allow the grass and trees to burn. As a result, today many forests have thicker vegetation（植被）.Thicker vegetation means more fuel（燃料）for fires. Also, without fires from time to time, forests become overcrowded and unhealthy. Some trees are dead. The dead wood then easily catches fire. So surprisingly, America has many more fires today partly because of its past fire-fighting practices.

Scientists now understand that a fire can be a natural part of a healthy forest. As a result, countries like Australia allow more fires to burn naturally. Sometimes, fire fighters even start fires to get rid of（去除）dead wood. Of course, they carefully control the fires. The fire thins out old trees. This allows sunlight to reach the ground. As a result, fires help new trees to grow. Therefore, if a fire is not a serious threat（威胁）to people, firefighters may let it burn naturally.

    Millions of children in the United States go to summer camps. Some go to play outdoors at traditional camps in the woods, in the mountains or on lakes. But families now have many choices of special camps. These can be in the middle of nature or a big city. Special camps offer young people the chance to learn about different subjects: Anything from space exploration to business to medicine.

    In technology camps, one subject that children can learn about is video game design. They learn how to use computer programmes to create games of their own. One programme that teaches video game design is called Cybercamps. Children can learn how to design their own virtual(实际上的) worlds to set their video game in. Then, they programme their own rules and objects into the game.

    Cybercamps also offers courses in robot building and Web design. A recent story in the Washington Post described how one child made a robot that could sing a song. Another made a robot that could follow a black line drawn on a piece of cardboard. Also, children can learn how to make Web sites. One child made a site for pokeman, one of his favourite cartoon shows.

    Many people may sometimes wish it could be summer all year round. However, as nice as summer is, we really need the other seasons as well.

    Then why do we have different seasons? We know that the Earth spins on its own axis (轴线). This makes day and night. In 24 hours the Earth turns round once. When we are facing the sun, it is day. When we face away, it is night. Simple!

    We travel around the sun in a circle. So why does it get colder in winter and hotter in summer? It's because the axis of the Earth is tilted (倾斜的). It means that in summer some places, such as the UK, are leaning towards the ssun. The temperature rises. As the Earth travels around the sun, these places begin to tilt away and the temperature drops. It becomes winter.

    This is why when the UK has winter, Australia has summer. Imagine having Christmas dinner on the beach! But not all countries have seasons. Countries near the equator (赤道), the line which goes round the middle of the Earth, don't have different seasons. The weather stays almost the same temperature all the year round. Can you think why this is? The middle doesn't tilt very much, does it? This means the seasons don't change much.

    Then what about the North and South Pole? What are the seasons like there? Because they get very far away from the Sun, their seasons are very extreme. There are only two seasons near the North and South Pole: winter and summer. What's more, they only have one sunrise and one sunset a year. It is dark for six months of the year and light for six months of the year. What problems would there be if you had to live somewhere that was dark for six months of the year and light for six months of the year?

How to make ice-cream in a bag

    What you need:

    I spoon of sugar, 1/2 cup of "half and half" (牛奶和奶油的混合物)，1/4 spoon of vanilla extract(香草精), d add 1 spoon of sugar, 1/2 cup of "half and half" and 1/4 spoon of vanilla extract to the small bag.

    Next, add three glasses of ice 10 the big bag. You can add more or less just to make sure that the small bag will be covered by ice.

    Then, pour about 1/2 cup of salt into the big bag. The salt helps the ice get cold so you can add more if necessary.

    When it's ready, place the small bag in the big bag and seal tightly(系紧). You need to shake the bag for about five minutes.

    Finally, take the small bag out. Be careful not to open it. Wipe off(擦去) any salt on the bag. Now open the bag. You can enjoy your ice cream. You can finish all of the work in less than ten minutes.