Since his students began using Quizlet, English teacher Tristan Thorne has noticed an improvement in their ability to learn and use new words. Quizlet is a learning App, a computer program you use on your mobile phone. It can help users build and test their knowledge of English words. Quizlet has word sets for millions of subjects. And, it is quickly becoming a useful mobile tool for language learners.

    Thorne teachers at Columbia University in New York City. Thanks to learning Apps, Jeff Strack, another English teacher, has also notice improvement in his students' ability to remember information. He teaches at Hostos Community College, also in New York. He and Thorne are part of a growing number of language educators adding mobile Apps to their classes.

    Strack and Thorne seem to agree that the days when teachers would not permit the use of mobile phones are gone. When they use Apps, language learners communicate more differently than in a traditional classroom. Users act on or respond to something, instead of just listening to new information.

    Thorne believes that Apps can help learners become more active in learning. For example, each week, his students are required to add vocabulary words into Quizlet for others to use. He says some Apps also make it easy for students to know their language strengths and weaknesses.

    The biggest improvement Strack has seen in his students is that they are much more active in whole-class or small-group discussions. “Apps let all students take part in the activity, whether it's a game, quiz or practice activity.” he says.

    Many existing learning Apps are designed for students of all ages and levels. Some are designed for group activities. some support independent learning. Still some are good for homework. Thorne says he especially likes Quizlet and three other Apps: QR Codes, Socrative and Evernote.

    Climate change will force exhausted birds migrating to Europe from Africa to travel further, with possibly disastrous consequences, according to a study.

    The annual voyage of some species, which fly north in search of food and suitable habitats, could increase by as much as 400 kilometers (250 miles), the research found. “Marathon migrations for some birds are set to become even longer,” said Stephen Willis, a professor at Durham University in Britain and the main architect of the study. “This is bad news for birds like the White throat, a common farmland bird. The added distance is a considerable threat. As temperatures rise and habitats change, birds will face their biggest challenge since the Pleistocene era (更新世), which ended 11,000 years ago,” he said in a statement.

    Some 500 million birds migrate each year from Africa, some weighing as little as nine grams (three-tenths of an ounce). To complete a voyage that can be thousands of kilometers long, birds have to fatten themselves up to twice their normal weight. Some even shrink their internal organs (收缩内脏) to become more fuel efficient, so any additional distance may be dangerous.

    The study finds that from 2007 to 2010, nine out of 17 species examined are going to face longer migrations, particularly birds that cross the Sahara Desert. Some birds travel the Sahara and the Mediterranean Sea in a one go, while others have a break in northern Africa before crossing. Many fly at night, when temperatures are cooler.

    A few — such as the Blackcap — have started to adapt by spending winters in Britain, but such behavior remains exceptional, the study said. The study forecasts that the migration distance of the Orphean Warbler will jump from 2,700 kilometers (1,700 miles) to between 3,050 and 3,350 kilometers (1,900 and 2,100 miles), with even longer increases for the Subalpine and Barred Warblers.

    Norman Borlaug, who is making a difference, is known around the world. He is often described as the man who has saved more lives than any other person in history. Norman Borlaug is considered the father of what has been called the Green Revolution. His ideas about agriculture increased crop production and ended hunger in many nations. Mr. Borlaug continues to be a leader among agricultural researchers.

    Norman Borlaug was born in 1914 on a farm in the American state of Iowa. In the middle of the 20th century, world population was expanding faster than food production. Experts said many people in developing countries would face starvation.

    Norman Borlaug was an agricultural researcher at the International Maize and Wheat Improvement Center in Mexico. He developed methods of growing wheat that increased the amount harvested by three times. He later repeated this success in India, Pakistan and Africa.

    His methods of farming saved millions of people who would have starved to death. Norman Borlaug was given the Nobel Peace Prize for his efforts in 1970.

    Norman Borlaug is still urging experts to think about the needs of people around the world. His latest concern is a disease in wheat called UG99. He says it has the power to destroy most of the wheat being grown around the world. He says reductions in agricultural programs have made it harder to take action against such threats.

    Mr. Borlaug's granddaughter Julie works at the center named after him at Texas A&M University in Dallas. She says his worry about food problems rises from the belief that hunger is unacceptable. She says Norman Borlaug still believes it is our responsibility as human beings to feed one another.

    Nelson Mandela is respected and admired around the world. And to South Africans he is a superstar. He is a hero who shocked the world by fighting for peace between races, despite the 27 years he spent in the prison of the South Africa's white, racist regime (种族主义政权).

    Mandela who won the nation's first all-race elections after the fall of apartheid (种族隔离) in 1994, retired in 1999. But he remains as popular as ever. His popularity has inspired an entire national industry. His portrait (肖像) has appeared at many places, including on some goods. His face has appeared on a South African coin, and some business leaders hope to build a statue in his likeness—the Statue of Freedom. It would stand taller than New York's Statue of Liberty.

    “His popularity is similar to that of John F. Kennedy with US or Winston Churchill in Britain, but few politicians in his times have achieved his level of admiration,” said Tom Lodge, head of the political science department of the University of the Witwatersrand, “What a skilled performer Mandela has been throughout his political career! He's a very, very clever man.”

    However, he is far from perfect. Most articles for his birthday, which appeared in every major South African newspaper on the day, briefly mentioned that Mandela did have his shortcomings.

    Then they returned to their flowing praises. “Through the ages, the human race has had its icons (偶像)—men and women who rose above ordinary people to inspire their generations,” The Mail and Guardian Weekly said. “In our generation, the gods presented us Nelson Mandela.”

    What makes a building ugly? Everyone's got their own opinion, so it's hard to say. Now, let's take a look at some of the world's worst buildings.

    The Torre Velasca

    The Torre Velasca in Milan is in the centre of Milan(Italy). The tower, which went up in the 1950s, is about 100 metres tall. Its design is actually a modern representation(代表) of a traditional Lombard castle, where the lower parts were narrower than the upper parts.

    The Mirador Building

    The Mirador Building in Madrid(Spain)was created by Dutch studio MVRDV and the Spanish architect(建筑师)Blanca Lleó.The building, which is a block of flats, opened in 2005. There is a large rectangular(矩形的)hole in the upper part of it, which is used by the neighbourhood as a meeting area and playground.

    The Prague TV Tower

    The Prague TV Tower is in Prague(the capital of the Czech Republic). It stands 216 metres high and looks a bit like a tall, thin space ship. Prague is famous for its architectural beauty, so when the tower was put up in 1985 by architect Vaclav Aulicky and engineer Jiri Kozak, many felt it didn't fit in.

    The Longaberger Basket Company

    The Longaberger Basket Company building is in Newark, Ohio(USA). The office block was opened in 1997 and looks like a very large basket. It's got seven floors and two handles(把手)at the top. The handles weigh about 150 tons. It may not be the ugliest building in the world but it's certainly one of the most unusual.

    Feeding birds is a popular way to watch wildlife. But experts say it might put wild birds at risk.

    Feeding birds is not necessary for their survival except in extreme weather conditions. Feeders(喂食器)can definitely help birds get through that kind of weather. But most birds eat insects and show little interest in bird feeders. For those birds, we can grow native plants in a natural environment. Birds which are fond of eating seeds will be more likely to come to feeders if there is some cover nearby. This lets them feed and then fly to protective areas, such as in trees.

    The most common mistake people make with their bird feeders is that they put feeders in places where birds are easily frightened by passers-by, risk being hurt by cats, or risk flying into windows.

    So set up a bird feeder at least one meter away from a window. That way, if a bird gets frightened, it won't get killed when it hits the glass. Owners of cats should keep them inside home so they can't hurt the birds.

    Some birds are more aggressive at feeders. They eat a lot and do not leave much food for other birds. A solution is to put the food in more than one place by using different kinds of seeds or fruits. This can also increase the number and diversity of birds in your neighborhood. But don't feed wild birds anything salty, like potato chips, or food that could choke them, like bread.

    Pay attention to food quality and freshness. Unprotected food left too long in feeders will turn moldy(发霉), which can kill wildlife.

    Another word of advice: Always provide a supply of clean water for birds, but use care when looking for the right birdbath. If the birdbaths are too deep for birds, putting a few large stones in the water can give the birds a place to sit.