In most parts of the world, many students help their schools make less pollution. They join “environment clubs”. In an environment club, people work together to make our environment clean.

    Here are some things students often do.

    No-garbage lunches. How much do you throw away after lunch? Environment clubs ask students to bring their lunches in bags that can be used again. Every week they will choose the classes that make the least garbage and report them to the whole school.

    No-car day. On a no-car day, nobody comes to school in a car. Not the students and not the teachers! Cars give pollution to our air, so remember: walk, jump, bike and run. Use your legs! It's lots of fun.

    Turn off the water! Did you know that some toilets can waste twenty to forty cubic (立方) meters of water an hour? In a year, it would fill a small river! In environment clubs, students mend those broken toilets. We love our environment. Let's work together to make it clean.

    I must have looked deep in thought, or as deep in thought as an 11-year-old man can, when my grandmother glanced up from her weeding to ask, “You have something on your mind, don't you?”

    “Yes, I was thinking that someday I want to be an Olympic speed skating champion like my hero, Eric Haiden, I want to be a doctor like my parents and I want to help children in Africa.”

    I immediately knew I had confided in the right person when a knowing smile broke across her face. “Johann, of course! You can do anything you want to do!” she said simply. And with my grandmother's support, I set out to pursue my passions.

    14 years later, I was well ready to take hold of my first dream: becoming an Olympic champion. The Olympics in 1994 were in my home country, Norway. As I entered the Olympic stadium, I wasn't the best athlete, and many had doubts about my ability to perform well. But I had something special working for me. I had a woman in the first row who believed in me following my passions just as much as I did. For the first time ever, my grandmother was going to see me skate.

    It happened. Breaking a world record, I won the gold.

    As I stood on the podium(领奖台) that I had dreamed about my entire life, a curious question popped into my head. Why me? Why did I win, given all the other incredible competitors out there? The reason had to be more than a grandmother who shared a belief in her grandson's dream. The question led me to only one answer: because I wanted to make a difference in the world, and with all the media attention on my success, I could.

    I immediately knew what that difference had to be: hope in the lives of the children in Africa. Six months earlier, I'd been invited to Eritrea as an ambassador for Olympic Aid.

    Skiing has always been a big part of Kamikaze shiffrin's life. Her dad ski raced all through college and her mom raced and coached skiing. The Siffrins taught Mikaela and her brother, Taylor. To ski at a very young age. At two and a half years old, Mikaela made her first ski run down her driveway on plastic skis.

    Mikaela loved skiing. From ages 8 to11, she did hundreds of training runs on small hills to learn the skills of slalom skiing (障碍滑雪). When Mikaela was 11, she began to learn at the Burke Mountain Academy, a Vermont boarding school for skiers. She took classes, studied, and practiced her skiing. According to Burke Mountain Academy headmaster Kirk Dwyer, "What separated Mikaela from others was the degree of her commitment (投入) to be the best. Mikacla practiced more than anyone and believed in herself then and now." At age 14, Mikaela began her international career when she raced in the world championship for13 and 14 -year-olds. And she won!

    By the time she was17, she had already won her first World Cup race. "Living away from home four and five months at a time can be difficult" Mikaela says. "But it can also be exciting. I'm getting to see the world." When Mikaela began ski racing in Europe, her mother, Eileen, stayed with her. She worked as her high school teacher while they were on the road. "She has always been a super-hard worker," says Eileen.

    For Mikaela, working hard is a full-time job. Even her off-season is work time. "If you want something, just try your best," she says. At the 2014 Winter Olympic Games in Sochi, Russia, 18-year-old Mikaela Siffrin became the youngest slalom skier ever to win an Olympic gold medal.

    Almost every second of every day an older adult falls in the United States. That's approximately 29 million falls per year and nearly 27, 000 deaths, according to the Centers for Disease Control and Prevention.

    Still in the stating stage, the Active Pelvis Orthosis (APO) system in Switzerland wants to make a lightweight, wearable exoskeleton (外骨骼) that could detect signs of balance loss and assist with balance recovery to keep the elderly wearer from falling, only when needed.

    Other exoskeletons, either in development or on the market today, assist with movement and make heavy objects feel lighter. Mobility-impaired people can walk again. But none of these devices predict what the wearer is going to do next and take measures to correct an unsteady move.

    The 3 kilogram (6.7 pound) exoskeleton was built entirely from scratch by the research team and is designed to be worn on the lower half of the body. A waistband connects to two movable carbon fiber braces (支架), each one positioned on the outer side of a leg. Tiny motors and so-called "adaptive oscillators" (适配振荡器) in the computer circuits use a special process to detect the, wearer's unique paces. That part takes just a few minutes.

    While wearing the exoskeleton, a person may feel the braces and the motors pushing slightly on their legs. If their paces go against normal, the motors create a force in the braces that cause them to stiffen up and push a little more strongly against the legs, which provides stability.

    In the next three years, the APO hopes to develop something that is commercially available.

    Donald Watson was a man who thought very much about the food he ate. He was born in Yorkshire, England, in September 1910. And he died in November 2005, at the age of 95. That is a very great age. Watson explained that it was because he never ate any food from animals.

    When he was a boy, Watson stayed on a farm. .He loved to see the animals. He said that they gave so much to people. And all the animals were so friendly. Then, one day, he saw a man killing a pig. He was very sad. From then on, Watson decided that he would never again eat meat. Twenty years later he decided that he wouldn't eat anything from animals, such as milk, cheese or eggs. He became vegan (素食主义者).

    Watson formed a group called "The Vegan Society". In its newspaper, The Vegan Society thought it was terrible and wrong to eat food from animals. At first, there were not many people who agreed with him. They thought it was crazy to do it. Most people thought it was too difficult and unhealthy. However, over time, more and more people began to agree with Watson and The Vegan Society.

    People become vegans for many reasons. Watson and his friend stopped eating because they loved animals. They believed that it was wrong to hurt another living thing.

    Now, people also become vegans for environmental reasons. Keeping animals takes a lot of resources(资源), including water and food. Also, in some places, people are cutting down trees to create more land for cows. By avoiding food from animals, vegans hope to protect these forest areas.

    Finally, just like Watson, some people believe that being a vegan is healthier. They believe that food from animals causes heart problems, a high body weight and many other health problems.