Today, we are told, children don't spend enough time in the fresh air. Many of them are addicted to screen on a computer or a TV—they seem to be living in a virtual world. They have lost touch with nature.

    But now 400 organizations in the UK, from playgroups to the National Health Service, are encouraging children to have some “wild time”. They want kids to swap at least 30 minutes of watching TV or playing computer games for time playing outside. Activities such as building dens, climbing trees, rummaging for conkers and playing hide and seek are just some of the things kids can do. Even if they live in a city, they can go on adventures in the garden or the park.

    Children often need a helping hand from mom and dad. They need to be shown what to do and where to go. Andy Simpson from National Health Service says, “We want parents to see what this magical wonder product does for their kids' development, independence and creativity, by giving wild time a go”.

    So despite the complicated world that young people grow up in now, it seems that going back to basics and experiencing “nature's playground” is what modern children need. David Bond from Project Wild Thing says, “We need to make more space for wild time in children's daily routine, freeing this generation of kids to have the sort of experiences that many of us took for granted”.

    This might sound a bit old fashioned to you or maybe, like me, it's made you think about sticking on your boots, getting outdoors and reliving your childhood. There is no age limit on enjoying yourself!

    On a Saturday morning earlier this September, the world got its first look at the Strati. This electric vehicle is unlike any other currently on the road. It rolls on four wheels, but its body and chassis(底盘) weren't built in a factory. Instead, Strati's designers used a technology called 3-D printing. It created those parts of the car in one piece, from the ground up.

    “Compared to a typical vehicle on the road, the Strati definitely looks different,” says Greg Schroeder, a senior research engineer at the Center for Automotive Research in Ann Arbor, Mich. He did not work on the new car. His organization studies trends and changes in th e auto industry.

    It took 44 hours to print the new car at the International Manufacturing Technology Show in Chicago. Over the next few days, the car's designers installed additional parts. These included the car's engine, brakes and tires. Then, early on September 13, Jay Rogers climbed into the car, started its engine and drove the vehicle onto the street. Rogers helped found Local Motors. It's the Arizona-based company behind the Strati. Two weeks later, his team printed a second Strati, and just as fast, at a fair in New York City.

    Justin Fishkin, a local Motors official, sees the Strati as a window into the future. Today, car buyers are limited in their choice of a vehicle. They can order only what car companies have already designed. But in the future, he says, you may be able to design your own car online and then get it printed to order.

    Manufacturing experts say 3-D printing has begun to revolutionize how they make things. The technology has been around for decades. But these machines used to be so expensive that only large companies could afford them. In the last few years, though, that has changed. Many of the machines are now inexpensive enough for small companies—or even individuals —to own. Some local libraries make them available to the public. High Schools are beginning to use them in classrooms. Wide access to these printers means people can now design and print a wide variety of new things.

    The car's printer is a one-of-a-kind device.

    The technology behind the 3-D printer used in Chicago is an example of additive manufacturing. This proce ss builds solid objects, slice by slice, from the bottom up. (“Strati” means layers, in Italian.) A mechanical arm moves a nozzle from one side to another, back and forth. As it moves, the nozzle deposits a liquid—often melted plastic or metal (but it could be food, concrete or even cells) —that quickly hardens or bonds to become solid or semi-solid. This creates a single, thin layer. Once a layer is complete, the printer starts depositing the next one.

     “There's a lot of interest in 3-D printing in the auto industry,” says Schroeder. Right now, the technology is particularly useful for building models of cars or car parts.

    To compete with current auto manufacturers, the 3-D printer would have to increase in a hurry, Schroeder says. By contrast, he notes, a Ford F-150 pickup truck rolls off an assembly line at a rate of roughly one per minute. To print as many Stratis would require many more printers. Schroeder says he doesn't see 3-D printing soon taking over for such high-volume manufacturing. But, he adds, “Who knows what will h appen in the long term?”

    Scientists at Oak Ridge National Laboratory in Tennessee designed the 3-D printer used in Chicago. Lonnie Love, a research scientist at the lab, led the effort.

    Additive manufacturing often is slow and expensive. It also may produce materials that are unreliable, Love says. So for two years, his team searched for ways to make 3-D printing better. They built new machines and tested them over and over.

    All of that work paid off: their new machine is fast and uses less expensive material than earlier printers. In addition, it prints a plastic embedded with fibers of carbon to produce a stronger material. This helps ensure the material won't crack or break under pressure.

    Founded in 1764 by French traders, St. Louis today is the fifteenth largest urban area in the United States. There are many attractive destinations for tourists.

American Kennel Club Museum of the Dog

    Dog lovers who visit St. Louis won't want to miss this 14,000-square-foot museum. Inside are over 500 paintings, prints, watercolors, and a variety of other dog art objects.

    The Museum is open year round, Tuesday through Saturday 10 AM to 4 PM, and Sunday 1 PM to 5 PM. Admission is $ 5 for adults, $ 2.50 for seniors, and $1 for children up to 14.

Anheuser Busch Brewery

    The Anheuser Buxch Brewery tour is not just for beer lovers. The tour includes the historic Brew House. Then the tour continues to the modern Bevo Packaging Plant. The best will be the Budweiser Clydesdale stables. The tours are always free.

Gateway Arch

    Designed by Eero Sarinen and Hannskari Bandel, it took over two years and 900 tons of stainless steel to build. It is the tallest of the country's National Monuments. The Arch is part of the Jefferson National Expansion Memorial. About one milion people per year come to the top of the Arch, where there is an observation platform providing a great view of the city.

St. Louis Zoo

    First version of the St. Louis Zoo opened in 1904 at the St. Louis World's Fair, but in the century since it has grown into one of the chief zoos in the world. The passenger train takes visitors around the Zoo, which contains over 9,000 animals of over 800 species.

    The Zoo is open every day but Christmas and New Year, with summer hours of 8 AM to 7 PM, and hours the rest of the year of 9 AM to 5 PM. Admission to the Zoo is free.

    Some people have the feeling that nothing can be done about their poor reading ability(能力）. They feel hopeless about it. Can you learn to read better or must you agree that nothing can be done about it?

    To be sure, people are different. You cannot to do everything as well as certain other people do. All the students in a class tried out for basketball, some would be very good players; others would be very poor; and many would be in between. But even the very poor players can become much better players if they are guided in the right way, and with plenty of practice. It is the same with reading. Some seem to enjoy reading and to read well without any special help. Others find reading a slow and tiring job. In between, there are all degrees of reading ability.

    Many experiments have shown that just about every poor reader can improve his reading ability. In these experiments, the poor readers were given tests of reading ability. After some of the causes of their poor reading were discovered, they were given special instruction and practice in reading. After a few months, another test of the same kind was given. In nearly all cases, these people had raised their reading scores.

    Do you believe in the power of music? If you're like most kids these days, you probably have an electronic device loaded with hundreds or even thousands of your favorite songs. At any moment in time, you can fill your headphones with the sounds of a particular song that suits your mood at that exact time.

    Are you getting ready for a big soccer match or do you need to get excited? Maybe some hip hop with a strong beat will do the trick! Besides, you might be ready to study for a big exam the next day. To calm your nerves and help you concentrate, a little bit of Mozart might make memorization more manageable.

    But is there any scientific evidence of these effects that music seems to have? You bet there is! Scientists have long recognized the power of music. Over the years, many studies have been conducted to examine in greater depth the nature and extent of the effects music has on people.

    For example, scientists at the University of Missouri have found that listening to music can have a positive effect on your mood. Their research gives scientific credibility(可信性) to the behavior that many people have already experienced on their own: listening to upbeat music can brighten your day and boost your mood.

    Other studies have shown that upbeat music isn't the only type of music that can be helpful, however. When people are sad or have suffered a personal loss, sad music can be helpful because people identify with the tone and lyrias(歌词) of the music. Likewise, people under a lot of stress or experiencing upsetting situations can benefit from listening to angry music. Although angry music might not help you if you're in a normal mood, its tone can benefit you when you are dealing with stressful and upsetting situations.

Brilliant Ways to Deliver Secret Messages

Many effective ways are used now to deliver secret messages. But in the past when the science and technology was not developing, especially during the war, how did people send secret and important messages?

Shoelaces

In the 1950s, the U.S. Central Intelligence Agency created a book of tips to teach spies ways to communicate in public. One tip: Lace up your shoes. Tied one way, the laces might mean "I have information": tied another, "Follow me". The spies could communicate while everyone else probably thought, "That guy can't tie his shoes correctly!"

Tattooed (刺文身) Head

Around 513 B.C., Histiaeus was forced out as the ruler of an ancient city. So he wanted to send a message to his supporters: Rebel against the king who took away his power.

Histiaeus called in a slave, shaved his head and tattooed the message onto the man's skin on the top of head. After the slave's hair grew back, he travelled to Greece with orders to shave his head again. Message received!

Orange Juice

In 1597, John Gerard was imprisoned in the Tower of London in England. He asked the prison guard to let him send letters written in charcoal (木炭). But then he wrote another message on top using the juice from an orange-which was only visible when the juice was dry and the page heated. With his invisible ink, he escaped successfully.

Songs

In the 1800s, African American slaves couldn't talk openly about their plans to escape to freedom—so they secretly sang about it.

Swing Low, Sweet Chariot might sound like a religious song. But for slaves, the "sweet chariot" was the code for the Underground Railroad, the network of people who helped slaves head to northern states and Canada. The song Wade in the Water warned escaped slaves to get in the water so dogs wouldn't smell them. With these songs, hundreds of people escaped slavery.