Sheridan is a town in Indiana, USA. There are lots of trees near the public schools in the town. Their leaves turn sunlight into energy.

    In Sheridan, the Sun not just provides energy for plants. It keeps schools running, too. The schools use solar panels(太阳能电池板) to turn sunlight into energy.

    The science behind solar energy is not new. But Sheridan Community Schools is the first school district (学区) in Indiana to be completely solar-powered. The district finished putting in solar panels for all three of its schools in 2016. Some of the panels can turn to follow the Sun across the sky.

    In 2008, fewer than 1,000 schools used solar power. By 2014, there were 3,727 schools with solar panels in the USA. These numbers come from a report by The Solar Foundation. Roxie Brown, a programme director there, said that the number of schools with solar panels has continued to go up since 2014.

    Solar energy has some advantages over other energy sources (来源). Sunlight is a renewable source, which means it won't run out. Solar panels don't harm the environment. Also, sunlight is free. So by using solar power, schools can save money on energy costs. Brown thinks more schools should run on solar energy. "The Sun is Earth's energy source," she says. "We're trying to make it the energy source for our houses, cars and schools, too."

    But using solar energy isn't always easy. Solar panels can be expensive to put in. The panels also take up space. But for many schools, going solar is worth it.

    In ancient Chinese stories, the moon is home to Chang'e and her pet rabbit Yutu. Now, Chang'e and Yutu are really there!

    On Dec. 2, 2013, the Chang'e-3 lunar probe（月球探测器）took off from Sichuan, China. On Dec. 14, 2013, it landed successfully on the moon. Several hours later, Yutu, China's first moon rover（月球车）, "walked" out of the probe and onto the moon.

    Yutu is a big robot that weighs 140 kg. It is about 1.5 meters long and 1.1 meters tall. It has six wheels and travels at 200 meters per hour.

    There are cameras on both Yutu and Chang'e-3. They can take pictures of each other. That's how Yutu got is first picture on the moon.

    Yutu and Chang'e-3 will explore（探索）the moon.

    Yutu can walk around and work for three months. It can look for natural resources（资源）on the moon. Chang'e-3 can work at the landing site for one year and it can watch the space from the moon.

    They both get energy from the sun. So they "get up" to work when the sun rises, and "go to sleep" at night.

    China is now the third country in the world to soft-land on the moon after the US and the former Soviet Union.

    Also, China is planning to send its Chang'e-5 lunar probe around 2017. The probe will fly back to the Earth and bring natural resources from the moon.

    When will China fly a human to the moon? There's no plan yet. But the door is now open.

    Populations of white-tailed deer(白尾鹿) are growing rapidly in many parts of the United States. As populations grow, food becomes a problem. Many deer die of hunger. Others grow up small and unhealthy. In search of food, hungry deer move closer to where humans live. They eat farm crops, vegetables and even trees. Besides, increased numbers of deer near roads can cause traffic accidents.

    People admire the grace and fast speed of deer. Most people don't want these animals to be hungry and ill. Should people take action to control the growing deer populations?

Should People Take Direct Action?

    Many people think that hunting(打猎) is the best way to control the animal populations. Wildlife managers will see if there's enough food in an area and decide its carrying capacity(容量). Then hunters with licenses are sent to help control the number of deer. Hunting is usually not allowed in cities or suburbs, however.

    Some people have the idea to catch the deer and move them to other places. But this method is expensive and requires finding another place that can accept the deer without breaking the balance of ecosystem(生态系统).

    Scientists are also working to develop chemicals(化学药品) to control the birth rate(率) in deer populations. But this plan works for only one year at a time.

Should People Take Indirect Action?

    Some suggest bringing in natural enemies of deer, such as wolves, lions and bears, to areas with too many deer. But these animals could also hurt dogs, cats, and even humans. Other communities have built tall fences(篱笆) around areas to keep out the deer. However, this is impossible for farmers.

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    Some people are against any kind of action. They support leaving the deer alone. Animal populations in an area naturally go up and down over time. Doing nothing means that some deer will die of hunger or illness. But finally, the population will reach a size within the carrying capacity(容量) of the environment. So, let nature go its own way.

    We all cry for water when we are thirsty. But do you know, in very hot, dry weather, plants also make very low sounds as if they are crying for help?

    You see, in a plant's stem there are several hundred "water pipes" that bring water from soil all the way up to the leaves. When the ground turns dry, it becomes harder and harder for plants to do this.

    In very hot days, plants have to get any water that they can get.

    Scientists Robot Winter has found out that when plants can get no water, their "water pipes" snap(发出声音). When that happens, the whole plant vibrates(颤动) a little.

    Robot knows that healthy, well-watered plants are quiet. He also knows that dry plants are many insects' favorites and they often attack(袭击) them. How do the insects know which are healthy plants and which are not? Robot thinks that the insects may hear the plants "crying" and they may come to kill them.

This is a new school in Shenzhen, Guangdong. There are 55 classes from Grade One to Grade Nine. It is big. In this school, the students can sleep in their classroom at noon.

After lunch, students put all the desks and chairs in the middle of the classroom. Then they get beds out of the drawers（抽屉）. At last, all the students find their beds to sleep. After five minutes, the classroom turns into a special（特殊的）bedroom! "It is good to have a rest in the classroom!" said Liu Mingming, a student of Grade Six.

The head teacher Luo Can got the good the idea of the drawer bed. "It can help students learn better in the afternoon.", she said.

"The idea is so great. Good school and good head teacher!" said Chen Hong, one of the parents in the school.