Against the assumption that forest fires in Alaska, Canada and Siberia warm the climate, scientists have discovered that cooling may occur in areas where burnt trees allow more snow to mirror more sunlight into space.

    This finding suggests that taking steps to prevent northern forest fires to limit the release of greenhouse gases may warm the climate in northern regions. Usually large fires destroyed forests in these areas over the past decade. Scientists predict that with climate warming, fires may occur more frequently over next several centuries as a result of a longer fire season. Sunlight taken in by the earth tends to cause warming, while heat mirrored back into space tends to cause cooling.

    This is the first study to analyze all aspects of how northern fires influence climate. Earlier studies by other scientists have suggested that fire in northern regions speed up climate warming because greenhouse gases from burning trees and plants are released into the atmosphere and thus trap heat.

    Scientists found that right after the fire, large amounts of greenhouse gases entered the atmosphere and caused warming. Ozone（臭氧）levels increased, and ash from the fire fell on far-off sea ice, darkening the surface and causing more radiation from the sun to be taken in. The following spring, however, the land within the area of the fire was brighter than before the fire, because fewer trees covered the ground. Snow on the ground mirrored more sunlight back into space, leading to cooling.

    “We need to find out all possible ways to reduce the growth of greenhouse gases in the atmosphere.” Scientists tracked the change in amount of radiation entering and leaving the climate system as a result of the fire, and found a measurement closely related to the global air temperature. Typically, fire in northern regions occurs in the same area every 80 to 150 years. Scientists, however, found that when fire occurs more frequently, more radiation is lost from the earth and cooling results. Specifically, they determined when fire returns 20 years earlier than predicated, 0.5 watts per square meter of area burned are soaked up by the earth from greenhouse gases, but 0.9 watts per square meter will be sent back into space. The net effect is cooling. Watts are used to measure the rate at which energy is gained or lost from the earth.

    You can tell a lot about a country from its passport. Color is the first give-away. Nations tend to pick colors that reflect their national character. New Zealand decorates its famous rugby team, its airline and its passports in the nation's favorite color—black. Many Islamic countries have green passports because of the importance of the color in the Muslim faith.

    But as well as a statement of national identity, color can show international cooperation. The British passport was originally a navy blue. But after Britain joined the European Union in 1973, it switched to burgundy red（酒红色）like other EU countries. The common color was supposed to make European passports instantly recognizable.

    But since colors can't be patented（专利）, nothing stops others with the same idea. A number of countries that long to join the EU have changed their passports to burgundy too. Meanwhile Britain has decided to leave the club. Its government has announced that the UK passports will return to navy blue after Breit（脱欧）.

    If you have a passport from Singapore or South Korea, you are in possession of one of the most powe3rful travel documents on earth. Passport power is measured by the number of countries the holder can access visa-free. Currently sharing first place in the power rankings, Singaporean and South Korean passports provide visa-free access to 162 countries each. British passport holders share fourth place in the power ranking with six other nations, each accessing 159 countries visa-free. Americans ranked fifth with access to 158. Somalia, Syria, Pakistan and Iraq are among the world's least powerful passports. Afghanistan is the lowest ranking of all, with visa0free access to just 26 countries.

    Having to get a visa is not a piece of cake. First there is the never-ending form. Then there are lengthy appointments and expensive fees. Some visas also require travelers to pre-booked flights to prove that they intend to return home.

    But there are unexpected advantages to some of the world's weaker passports. Middle-ranking Namibia is one of just a handful of countries, whose citizens can enter Angola visa-free. India is one of only three countries, whose citizens have visa-free access to Bhutan.

    A low-ranking passport limits your choices, but not your sense of adventure.

    Moksh Jawa, 16, a student at Washington High School in the US, has already become a legend(传奇) among students. “Why not?” might be his favorite question to ask.

    As a seventh-grader, he taught himself coding(编程) by studying on the Internet.

    As a high school freshman, he passed the AP Computer Science A exam with a 5, the highest score possible.

    As a sophomore (高中二年级学生), he developed his own online course and helped his classmates get through it because his high school didn't teach coding.

    Everything he did came from his own interest. His father sent him a link to Codeacademy, an online coding training program, in middle school. He learned a programming(编程) language all by himself after signing up to the website.

    “I just fell in love with computer science,”Jawa said. Along the way, he lit a fire of curiosity and passion among classmates to learn coding too.

    “All of my friends, especially the girls, were really, really afraid of computer science,” he said. But the subject and exam weren't things to be feared, he said, “Computer science is all about logic(逻辑), not about how smart you are. ”

    To make his knowledge available online, Jawa set about creating his own online course, with easy-to-follow lessons. He included quizzes and tests too.

    The course has so far attracted 3, 200 students across the US and in 120 countries and regions, including China, Ukraine and Algeria.  It shows, Jawa said, the huge need for coding lessons.

    When video lecturing, “I deliver it like I'm talking from one high school student to another,”Jawa said. “It's always great to make it as clear and fun as possible, and to try to keep my voice as energetic as possible. ”

    He also does that, when teaching members of the computer science club he founded at his high school.

    “His tutorials(辅导) were great, ”said Taj Shaik, the club's co-president, who took the whole course last year. “I'm definitely one of the early adopters(使用者) of Moksh. ”

    “He's pretty amazing, ”said Bob Moran, principal of Washington High School, who saw him lead the club. “He was just a fantastic teacher—clear, organized and entertaining. When a student got the right answer, he would throw him a candy. ”

    Samuel Osmond is a 19-year-old law student from Cornwall, England. He never studied the piano. However, he can play very difficult musical pieces by musicians such as Chopin and Beethoven just a few minutes after he hears them. He learns a piece of music by listening to it in parts. Then he thinks about the notes(音符) in his head. Two years ago, he played his first piece Moonlight Sonata（奏鸣曲）by Beethoven. He surprised everyone around him.

    Amazed that he remembered this long and difficult piece of music and played it perfectly, his teachers say Samuel is unbelievable. They say his ability is very rare, but Samuel doesn't even realize that what he can do is special. Samuel wanted to become a lawyer as it was the wish of his parents, but music teachers told him he should study music instead. Now, he studies law and music.

Samuel can't understand why everyone is so surprised. "I grew up with music. My mother played the piano and my father played the guitar. About two years ago, I suddenly decided to start playing the piano, without being able to read music and without having any lessons. It comes easily to me —I hear the notes and can bear them in mind—each and every note," says Samuel.

Recently, Samuel performed a piece during a special event at his college. The piece had more than a thousand notes. The audience was impressed by his amazing performance. He is now learning a piece that is so difficult that many professional(专业的) pianists can't play it. Samuel says confidently, "It's all about super memory—I guess I have that gift."

    However, Samuel's ability to remember things doesn't stop with music. His family says that even when he was a young boy, Samuel heard someone read a story, and then he could retell the story word for word.

    Samuel is still only a teenager. He doesn't know what he wants to do in the future. For now, he is just happy to play beautiful music and continue his studies.

    Did you know that badminton is also a fast-paced competitive sport? Badminton has been a Summer Olympic sport since 1992. Para-badminton will be included in the 2020 Summer Olympic Games in Tokyo. Here's what you need to know if your child is interested in badminton.

    Badminton is played on a 44-foot-long rectangular (矩形的) court that is 17 feet wide for singles and 20 feet wide for doubles. It is divided in the middle by a net placed 5 feet off the ground, like volleyball, not at ground level like tennis.

    In competition, each match is a set of three games played to 21 points. There is a one-minute break when a player or team reaches 11 points, and a two-minute break in between the first and second games and the second and third games.

    Age kids can start: About 6 years old.

    Best for kids who: Have good skills, are patient and hardworking, and can handle the pressure of one-on-one or two-on-two competition.

    Team or individual: Matches can be singles (one-on-one) or doubles (two-on-two).

    Fun fact: Badminton is the only sport that has mixed doubles event in the Olympic Games.

    Costs: Beginners are expected to pay $30 to $40 for an entry-level racket (球拍). Badminton shoes are similar in price to other athletic shoes. Join a club or team for lessons and court time. A one-hour group lesson for beginners should cost $20 to $25, with costs increasing as your child moves up the ranks. You will also pay entry fees for competitions.

    Time commitment required: Beginners will play for just an hour or two per week.

Potential for injury: Players have a very low risk of injury. Players who wear glasses should use eye protection.

    I was in the seventh grade, and we had moved to New Jersey in November. By then, everyone already had had their own friends, and no one wanted to talk to a new girl. To make things worse, they put me in "Section L". I found out later that everyone called Section L "Loserville". It was sort of an open secret that it was the section for troublemakers and not-so-smart kids. When I found out, I wanted to scream. I had always been a good student and had amazing friends, and now everyone thought I was a loser!

    I did text my friends in Illinois almost every night, especially my best friend, Ana. At first my friends wanted to hear all about it. But then some stopped texting back once I said something about how miserable I was. One night when I was texting with Ana, I complained about another friend who had just done that.

    Ana's texts came really fast for the next few minutes and they surprised me. She said that she was tired of hearing about how bad everything was in New Jersey, too. She said she did not want to hurt my feelings but that I needed to stop feeling so sorry for myself all the time, I had to try to make things better.

    The next day, I thought a lot about what Ana had said. She was right!

    I wish I could say that everything changed overnight after that, but it didn't. I was still stuck in "Loserville", and some people were still mean to me, even though I tried to just stay out of their way.

    But what did change was me—I stopped feeling so sorry for myself and did something about making friends. I signed up to make sets for the school play. I met a lot of new people there, and suddenly I had friends to say hi to in the halls!

    I still miss Illinois sometimes  but life in New Jersey isn't so hard anymore. Even though I couldn't change my situation, I could change my attitude—and that made all the difference.