【推荐1】Some years ago, George Bruce, an American professor, was traveling at the Yellowstone National Park. “When I was admiring the scenery（风景）, someone came to the front, took many pictures and walked away,” he recalls（回忆）as he shares his traveling experience. “She didn’t even look at the scenery! It’s just like, ‘Got it-Done!’” Bruce is surprised by how much people depend on pictures for their memories. These days, people take pictures before dinner, during friends’ birthday parties and so on. They believe taking photos will help them remember the moment. However, according to Bruce’s research, the opposite is true.

In his study, Bruce led two groups of students around a museum. One group could use cameras while the other couldn’t. The next day, he tested the students’ memories of the tour. He found that the group that took photos remembered less information about the exhibits（展品）than those who didn’t. Bruce explains that when people tie to their cameras, they pay less attention to the things themselves. As a result, they often fail to remember their experiences well.

So taking pictures may stop our brains from remembering things and places. “In order to remember well, we have to review the photos carefully,” Bruce says. However, most people never take the time to review pictures. Why? There are just too many of them!

【推荐2】Do you know the reason why we feel tired in the middle of a class? Maybe you would say it is because the teacher’s class is boring.     1     Perhaps this is something you have not paid enough attention to or not yet noticed.

Purpose of sleep.

    2     Sleep helps our body heal（修复）, grow, and stay healthy. It also gives us energy, so we can be active all day. Doctors and health scientists say: When you close your eyes and need to rest, sleep is just the very best! This is more than advice.

Sleep time.

Enough sleep is important to us. How much sleep do we need? New-born babies sleep most of the time. They can sleep 20-22 hours a day. Children need 10-12 hours of sleep a day. Teenagers need 8-10 hours of sleep a day because they need lots of energy to grow into their adult（成人的）bodies. Grown-ups usually need 6-8 hours of sleep to keep active.     3    

Interesting facts.

Almost everyone has their dreams while they sleep, but not all of them can tell their dreams clearly when they wake up.     4     More surprisingly, some may even get up in their dreams and walk around. This is called “sleepwalking”. Are you a sleepwalker? Or, is there a sleepwalker around you?

    5    

It’s not just people that love to snooze（打盹）. In fact, many animals have unusual or surprising sleeping habits. Some animals, such as bears and hedgehogs, sleep all through winter. The swift is a very fast bird that can sleep while it flies! Cute koalas sleep around 18 hours a day. Giraffes don’t need much sleep at all. They usually sleep standing up.

What subject do you worry about the most at school? Many student worry about math. Some student can’t sleep well the day before a math exam. Others may feel very nervous during the math exam. But do you know the right postures might be a way to make you less nervous?

Postures mean the ways you sit in front of your desk. When you study, maybe you changes your postures all the time. Sometimes you slump over or sit up straight. Or sometimes you lie on your back or put your head on your desk.

For those students who feel like a deer in the headlights before taking a math test, a simple change in posture could make a big difference.

Scientists have tested 125 college students. They ask the students to do a sample math test while sitting in a slumped over position ,or sitting up straight. After the test, 56% of students say the exam is easier to do if they are sitting up straight.

The findings are that the slumped-over position shuts the students down so that they cannot think clearly. The slumped-over position also can bring the students bad memories. While sitting up straight can help students do better on math exams.

Students who are not nervous about taking the math exam do not necessarily get help from better postures. But they do find that doing math while slumping over is more difficult.

These findings about body position can help people prepare for many different types of performance under stress, not just math tests. So when you feel stressed out, you can also try to sit up straight or stand tall. It can help you feel more positive and focus better.

【推荐2】When a computer runs a group of programs, it can get very hot. Cooling the computer can cost a lot, so some scientists want to know one thing: What would happen if they use the heat(热量) from the computer?

Large Internet companies such as Google and Microsoft have thousands of computers. As people use these computers to look through information, they produce lots of heat, so they need huge cooling systems(系统).

These systems send the heat into the air. A Company in Holland(荷兰) thought paying to make the computers work and then paying again to cool them were a waste of energy. So the company developed a special machine—the e-Radiator. Boaz Leupe, head of the company, says that the eRadiator works as a heating system and saves money. He says that the energy is used twice—once to heat the home and once to cool the computer. He also says that users don’t have to pay to cool their computers. Five homeowners(房主) in Holland are testing the heating system in their homes. “We pay for using the computer, so, in that way, homeowners get heat for free,” Boaz says. Jan Visser is one of the homeowners. “If you use the computer more, the e-Radiator produces more heat,” he says. “It cannot provide enough heat if you don’t use your computer often.” But he is ready to try it. It’s a great help for his family.

The company says e-Radiators produce heat of up to 55°C. It says the system could save its users about $440 a year. That’s really wonderful, right?

【推荐3】Computers are wonderful machines. The Internet is also wonderful. But some people spend too much time online. They can’t stop. Doctors say this is a new illness called Internet Addiction Disorder (互联网成瘾症) .

People with IAD are online a lot. They spend many hours chatting with their friends or playing games online. Many people with IAD spend more time surfing the Internet than staying with their families or friends. Some people with IAD even give up their jobs!

Do you have IAD? Think about the following questions carefully: How many hours a day are you online? When you are not online, do you want to play computer games or check your messages? When you are online, do you often lose track of time? Do you get angry when you can’t play computer games?

If you have IAD, what should you do? Dr. Ivan Goldberg and Dr. Kimberly S. Young give some advice. First, ask yourself, “Why am I online a lot?” Then try to take a break. For example, use the computer or play computer games twice a week, not every day. In this way, you can spend more time with your families or friends.