Some educators told us that more years of school could help students get higher scores on intelligence tests. That was a finding of a study of teenage males in some countries. Now, another research shows that physical activity may help students do better in their classes.

    The research comes as educators in some countries are reducing time for activities like physical education. They are using the time instead for academic（学术的）subjects like math and reading. The studies appeared between 2008 and 2014. They included more than 55, 000 children, aged 6 to 18.

    Amika Singh:“ According to the results of our study, we can conclude that being physically active is beneficial for academic performance. There are, first, Physiological explanations, like more blood flow, and so more oxygen to the brain. Being physically active means there are more hormones(荷尔蒙)produced like endorphins(内啡肽). And endorphins make your stress level lower and your mood improved, which means you also perform better.”

    Also, students taking part in organized sports learn rules and how to follow them. This could improve their classroom behavior and help them keep their mind on their work.

    The study leaves some questions unanswered, however. Ms. Stash says it is not possible to say whether the amount or kind of activity affected the level of academic improvement. This is because of differences among the studies.

    The researchers said they found only two high-quality studies. They needed more high-quality studies to confirm (证实) their findings. They also pointed out that “results for other parts of the world may be quite different.”

    Still，the general finding was that physically active kids are more likely to do better in school. Ms. Singh says schools should consider that finding before they cut physical education programs. Her paper on “Physical Activity and Performance at School” is published in the Archives of Pediatric and Adolescent Medicine.

    One of the most exciting and interesting international cities to visit is London, England. Here is a look at four free things to do during a vacation to London.

    Visit the Trafalgar Square

    Built more than 200 years ago, Trafalgar Square is a popular gathering place for locals and travelers, too. The area is close to good shopping and dining opportunities, and there are usually some sorts of public events or celebrations going on there during most weekends.

    Wander Along the Thames

    Visitors wanting to see some great architecture, attractions and views should spend an afternoon walking along the River Thames. The best place to start is at the world-famous London Bridge crossing over the river and you can walk all the way to Westminster Bridge a short distance away. Travelers doing this will find themselves passing by a great many historic buildings.

    Explore the Local Markets

    While purchasing items at any of the open markets in London is not necessarily free, walking through them to view the merchants, their products and the other shoppers is of great fun. Some of the popular open markets in London worth visiting include Spitafields Market, Portobello Road Market and Leadenhall Market.

    Visit the British Museum

    One of the top museums in the entire United Kingdom can be found in London, and it charges no admission for entry. This museum is so highly regarded that it is not only popular with locals and tourists, it is also seen as a major and valuable scholarly resource.

    Whenever we see a button on a doorbell or on a remote, we may press it. This is true in most cases. But some buttons are actually fake(假的), like the "close" button on an elevator.

    Many people are in the habit of pressing the "close" button because they don't have the patience to wait for the elevator doors to shut. But according to experts, the buttons are a complete trick—the doors will not close any faster however hard you press.

    It started in the 1990s when the Americans with Disabilities Act was passed, making sure that all elevators stayed open long enough so that people with disabilities could enter. Only firefighters and maintenance workers(维修工) can use the buttons to speed up the door-closing process if they have a code or special keys. But to normal elevator riders, the buttons aren't completely useless.

    According to psychologists, fake buttons can actually make you feel better by offering you a sense of control. Experts have showed that a lot of buttons that don't do anything exist in our lives for this same purpose. For example, pedestrian crosswalk buttons don't live up to their names. Pressing them used to help make the traffic signals change faster, but that was before computer-controlled traffic signals were introduced.

    But psychologists found it interesting that even when people are aware of these little "white lies". They still continue to push fake buttons because as long as the doors eventually close, it is considered to be worth the effort.

    That habit is here to stay, John Kounios, a psychology professor at Drexel University in the US, told The New York Times. "After all, I've got nothing else to do while waiting. So why not try the chance?"

    People usually visit cafes to ease themselves of their tiredness and keep themselves from falling asleep, but Mr. Healing, a popular cafe chain in South Korea actually does the opposite. Customers can come in, order a drink, lie down in a comfortable massage chair, and take a nap.

    Many Koreans suffer from a lack of sleep as a result of overworking, so any opportunity to relax and even take a nap is greatly appreciated. Mr. Healing is the perfect place to go when you're on a short work or school break and you need to catch up on sleep. The cafe offers massage periods in various modes, depending on how much time you have and how you choose to spend it.

    The 20-minute session is priced at $3.5, the 30-minute massage costs $7, and the 50-minute session is $9, all of which also include a drink. Once you make your choice, you are taken to the “healing center”. You are asked to take off your shoes as well as any jewelry that might damage the chairs, after which you can choose a massage mode, from “stretch” or “sleep”. You can start with stretch for a few minutes, and then switch to sleep if you want to take a short nap. After it comes to an end, you are taken back to the cafe area to enjoy a coffee or one of the many other refreshing drinks on the menu.

    Mr. Healing cafes are so popular in Korea that customers are advised to make reservations in advance to be sure that a massage chair is available. “I have to sit on a chair and stare at a computer monitor all day due to my job, the healing room was truly effective to relieve tiredness and stress from weekdays,” said Park Hye-sun, a 24-year-old officer.

    Some have described Mr. Healing and other similar relaxation cafes in South Korea as simple fashions, but others see them as a sustainable business model, because they offer a service that Koreans really need.

    War can be deadly for wildlife, too. A new study reports that war is the biggest threat to Africa's elephants, rhinoceroses, and other animals. Researchers examined how years of conflict in Africa have affected populations of large animals. More than 70 percent of Africa's protected wildlife areas have been within a war zone at some point in the last 70 years. The more frequent the fighting, the greater the drop in animal populations, said Josh Daskin, an ecologist at Yale University. He was the lead author of the study, which was published Wednesday in the journal Nature.

    It takes very little conflict, as much as one conflict in about 20 years, for the average wildlife population to be declining, Daskin said. "Areas with frequent fighting — but not necessarily the bloodiest fighting—lose 35 percent of their large animal populations during each year of war," he said.

Some animals get killed by weapons of war. Yet, many also die because of changes in social and economic conditions in an area as a result of war, said Rob Pringle. He is an ecologist at Princeton University and the study's co-author. "People in and around war zones are poor and hungrier. So they may begin to illegally hunt animals for valuable tusks or hunt protected animals to eat," Pringle said. "And during wartime, animal conservation programs do not have as much money or power to protect wildlife."

    The new study examined the entire African continent over 65 years. The researchers looked at 10 different factors that could change population numbers. They included war, drought, animal size, protected areas and human population density. The number of wars had the biggest effect on wildlife population. The intensity of the wars — measured in the number of human deaths — had the least effect on animals.

Lack of sleep among children and teenagers in China has worsened in the past decade, with more than 80 percent getting insufficient sleep on school days, a new report has found.

Chinese youngsters snooze 7. 8 hours a night on average on school days, down 0. 3 hours from 2009, according to the report released on Monday by the Chinese Academy of Sciences'Institute of Psychology.

Researchers surveyed more than 15,800 students from Henan, Hebei and Guangdong provinces from April to July, asking what time they go to bed and wake up on days they take offline classes on campus.

Only 46. 4 percent of them sleep for at least 8 hours, compared with 47. 4 percent in 2009.

According to an action plan laying out measures to be taken from 2019 to 2030 to promote the health of citizens, primary school students are recommended to get a minimum of 10 hours of sleep a night. For junior high school and senior high school students, the recommended sleep durations per night are 9 and 8 hours respectively.

By this set of standards, more than 95 percent of students from primary schools, nearly 91 percent at junior high and 84 percent at senior high, did not get enough sleep on school days, heightening the risk of them developing cognitive, mental and physical health problems, the report said.

Hou Jinqin, a researcher at the National Institute of Education Sciences who co-authored the study, suggested local authorities implement measures instructed by the Ministry of Education, such as lessening academic burdens, postponing start times at school and encouraging children to be enrolled at institutions closer to home, in order to prolong sleeping hours.

In terms of the COVID - 19 outbreak's impact on sleep, she said available research overseas shows school closures forced by the COVID - 19 epidemic have added two hours of sleep to young students studying-gat home.

In China, some studies have revealed no marked differences in sleeping patterns of students before and after school reopened, she added.