Do other countries' students also have so much homework? What do they usually do in their free time? You may feel curious about them.

    On April 8, a report came out on the lives of high school students in China, Japan, South Korea and the US. It surveyed around 6,200 students from the four countries last year. You will find the answers to many of your questions in this report.

    Who studies hardest?

    Chinese students spend the most time studying. Nearly half of Chinese students spend more than two hours on their homework every day. That's much more than the stud the US (26.496), Japan (8.2%) and South Korea (5.2%).

    Who sleeps most often in class?

    Japanese students fall asleep in class most often. About 45% of them said they sometimes doze off in class. In South Korea, it's 32%; in the US, 21%; and 5% in China.

    South Korean students don't like taking notes. About 70% said they write down what the teacher says in class, many fewer than in Japan (93%), china (90%) and the US (89%).

    Who is the most distracted (走神)?

American students are the most active in class, but also the most distracted: 64.2% said they chat with friends in class; 46.9% said they eat snacks in class; and 38.9% said they send e-mails or read unrelated books in class.

What do they do after school?

    In their spare time, most Chinese students study or surf the Internet. Most American students hang out with their friends. Most Japanese students do physical exercise. Most Korean students watch TV.

    Do you know how it is when you see someone yawn and you start yawning too? Or how hard it is to be among people laughing and not laugh yourself? Well, apparently it's because we have mirror neurons (神经元) in our brains.

    Put simply, the existence of mirror neurons suggests that every time we see someone else do something, our brains imitate it, whether or not we actually perform the same action. This explains a great deal about how we learn to smile, talk, walk, dance or play sports. But the idea goes further: mirror neurons not only appear to explain physical actions, they also tell us that there is a biological basis for the way we understand other people.

    Mirror neurons can undoubtedly be found all over our brains, but especially in the area which relate to our ability to use languages, and to understand how other people feel. Researchers have found that mirror neurons relate strongly to language. A group of researchers discovered that if they gave people sentences to listen to (for example: “The hand took hold of the ball”), the same mirror neurons were triggered as when the action was actually performed (in this example, actually taking hold of a ball).

    Any problems with mirror neurons may well result in problems with behavior. Much research suggests that people with social and behavioral problems have mirror neurons which are not fully functioning. However, it is not yet known exactly how these discoveries might help find treatments for social disorders.

    Research into mirror neurons seems to provide us with ever more information concerning how humans behave and interact. Indeed, it may turn out to be the equivalent for neuroscience of what Einstein's theory of relativity was for physics. And the next time you feel the urge to cough in the cinema when someone else does-well, perhaps you'll understand why.

    The number of giraffes is becoming smaller across Africa, according to the Giraffe Conservation Foundation. The total population has dropped by 40 percent in the last 15 years. Surprisingly, even scientists haven't given much attention to giraffes. We are learning more about their ecology, but what we know is still way behind what we know about other species. "It's a silent extinction," said Dr. Julian Hennessy, a wildlife scientist.

    "The main reason for the smaller number of giraffes is their loss of living places," said Hennessy, "as an increasing part of land is used for farming. But hunting also has a big influence." You might wonder why hunters would focus on giraffes. First of all, once a giraffe is brought down, there is lots of meat with a small amount of effort. Besides, there is another thing encouraging the hunting. In Tanzania, Hennessy says, the latest word on the street is that eating giraffe meat could cure AIDS. Fresh giraffe heads and bones can be sold at prices of up to $140 per piece.

    Another widespread misconception about giraffes is that they are everywhere. Look at kids' books which are full of giraffes. They are always in zoo collections. They can be seen easily, so you don't think we have to worry about them. But the truth is that they are in danger of extinction. There is a lack of right and true data.

    Hennessy and other researchers are now pulling together the data needed to improve the situation of the entire giraffe species and all nine subspecies (亚种). The information will be used to change the giraffe's listing on the International Union for Conservation of Nature Red List, which now lists the species as of "least concern" but two subspecies as "endangered". "It's a lot of work to gather the necessary information," Hennessy says. "And several other giraffe subspecies will be recommended for endangered listings next year or the year after." He hopes that the world will finally start to take notice of how endangered these beloved animals have become.

    The bus screamed to a stop in Nazareth, Israel. Five Australian backpackers boarded and struck up a conversation with me. They asked typical travelers' questions—where was I going and why was I traveling alone? My plan was to travel with a friend of a friend, I explained, but when I called her that morning, she didn't pick up and I had no other way to reach her. My stomach was in knots, but I decided to head out anyway, thinking I might run into her if I traveled to Tiberius, where we had planned to go together.

    "Why don't you travel with us?" one of the backpackers offered. They were experienced adventurers who would work for a few months, save, then travel for as long as they could. Their current plan was to explore the Middle East and Europe in three months while working in London.

    It seemed risky to travel with strangers, but my instinct said yes. For the next two weeks, I explored Israel with the backpackers and learned to trust my instincts in all types of new and interesting situations. When they hook a ride, I took the bus, but when they wanted to steal into the King David Hotel's swimming pool, I led the way. The world opened up to me because I chose to travel alone. I joined complete strangers, who become close friends. Years later, one couple from the backpacking group even flew from Sydney to Phoenix to be in my wedding. The trip was such a special experience that it gave me confidence in all areas of my life. Since then, I've backpacked alone across South Africa, sky-dived from 12,000 feet in New Zealand and even moved across the U.S. with no job lined up.

    On my third day wandering in Israel with my new friends, I bumped into the woman I was supposed to meet. Though I was happy she was all right, I was grateful she hadn't picked up the phone.

    Although not as much as in the past, grandparents are the teachers of the Navajo (纳瓦霍人) youth. They make young people aware of life at an early age. The parents grant them the privilege of teaching the children, and the grandparents take great pride in raising the children or at least having a big part in raising them.

    Young children often stay with their grandparents for years at a time developing a close and trusting relationship. The grandparents teach the children Navajo legends and the principle of life, emphasizing both new culture trends and the preservation of traditions.

    The grandparents are also often the leading figures in teaching the youth the arts of weaving, caring for the livestock, using herbal medicine, and other arts and crafts.

    The children are taught to respect their elders, to care for them, to help them whenever they are in need, and to learn from them. Young people are urged to listen with care to the words of their elders and to keep as much wisdom as possible. Grandparents often go to social gatherings and traditional events, and the young have opportunities to learn more about their culture and traditions.

    I live with my grandmother for thirteen years, and she raised me in the old ways of our people. Although I was going to school, she taught me as much as she could about our traditions. She was a beautiful woman. If I had a chance, I would listen again to her wise teachings, expressed with kindness in a soft voice that touched my heart.

    We used to plant corn and pumpkin every summer. They never grew big enough to feed us, but we planted them anyway. I asked my grandmother why. She said, "Grandson, our plants will be far more beautiful than the flowers outside the fence." I did not understand until one day I saw their beauty as I was coming over the hill with her. She said, "Anything that is a part of you is always far more beautiful than the things which you pass by." We had some beautiful years together. I am glad she is a part of me and I am a part of her.

    Children used to be well disciplined, possessing more respect for culture, tradition, and beliefs than they do now. The world of the Navajo has been influenced by the western world, and the grandparents have less control and influence than they used to. But the young people who have been touched by their teachings have glimpsed a way of life beyond what most people know today.

    A few weeks ago, I called an Uber to take me to the Boston airport for a flight home for the holidays. As I slid into the back seat of the car, the warm intonations(语调) of the driver's accent washed over me in a familiar way.

    I learned that he was a recent West African immigrant with a few young children, working hard to provide for his family. I could relate: I am the daughter of two Ethiopian immigrants who made their share of sacrifices to ensure my success. I told him I was on a college break and headed home to visit my parents. That's how he found out I went to Harvard. An approving eye glinted at me in the rearview window, and quickly, we crossed the boundaries of rider and driver. I became his daughter, all grown up—the product of his sacrifice.

    And then came the fateful question: "What do you study?" I answered "history and literature" and the pride in his voice faded, as I knew it might. I didn't even get to add "and African-American studies" before he cut in, his voice thick with disappointment, "All that work to get into Harvard, and you study history?"

    Here I was, his daughter, wasting the biggest opportunity of her life. He went on to deliver the age-old lecture that all immigrant kids know. We are to become doctors (or lawyers, if our parents are being generous)—to make money and send money back home. The unspoken demand, made across generations, which my Uber driver laid out plainly, is simple: Fulfill your role in the narrative(故事) of upward mobility so your children can do the same.

    I used to feel anxious and backed into a corner by the questioning, but now as a junior in college, I'm grateful for their support more than anything. This holiday season, I've promised myself I won't get annoyed at their inquiries. I won't defensively respond with "but I plan to go to law school!" when I get unrequested advice. I'll just smile and nod, and enjoy the warmth of the occasion.