The United States has always been a country of many cultures. Before Europeans came to North America, many groups of Native Americans lived here. Different Native American groups had different cultures. The first Europeans in the United States were from England and Holland, but immigrants came from all European countries. Many people also immigrated from Asia and Africa. Sadly, many Africans were brought to the United States as slaves. Many immigrants come from Latin America too. Today, the United States has people from more cultures than ever.

    In the 19th century, people spoke of the United States as a “melting pot.” People thought that all immigrates should forget their native cultures and languages and become English-speaking Americans. They felt that people should assimilate-join American culture. However, not everyone wanted to assimilate completely. Many people tried to keep parts of their cultures, such as foods, customs, and languages. However, their children often forgot their parents' or grandparents' language. But most Americans, even those whose families have been here a long time, can tell the countries their relatives came from. And of course, new immigrants take great pride in their curare and language.

    For all of these reasons, melting pot is no longer a good way to describe the United States. Instead, people now call the United States a “salad bowl.” They say salad bowl because in a salad, you can still see all of the individual parts (lettuce, tomato, and so on), but all the different parts mixed together and begin to take on the flavor of one another.

It's almost camp season!

    Summer is wonderful. Summer at one of the following awesome camps? Even more wonderful.

Tahosa High Adventure Base

    Location: Ward, Colorado

    People puzzle: Tahosa's ropes courses are some of the nation's best. Use your hands, feet and brains to take up high-flying challenges and overcome your fears. Fly fishing at 9,000 feet? Yes. Fishing licenses or experience needed? No, sir!

    Choose your adventure: Go all-inclusive, where the staff prepares meals and runs the program, or take control and plan your perfect week. The choice is yours.

Camp Raymond

    Location: Parks, Arizona

    Don't look down: When looking up at the stars, light pollution is your enemy. But Camp Raymond's location and elevation (海拔) of 6,700 feet offer perfect conditions for seeing otherwise invisible stars.

    That's cool: Don't forget your camera and a jacket. During the day, you could spot bears and deer. At night, temperatures can fall sharply. Hot cocoa at summer camp? Cool.

Pamlico Sea Base

    Location: Blounts Creek, North Carolina.

    Go coastal: Explore the Carolina coast by boat. You choose the route, and Pamlico provides the equipment. Keep an eye out for wild horses, lighthouses and boatloads of fish.

    Set sail: Even if you don't know the difference between starboard and star-lord, Pamlico's sailing journey will make you a first-rate sailor in no time. You'll even practice finding your way using the stars.

Base Camp

    Location: St. Paul, Minnesota

    Big upgrade: What happens when you change a 1907 cavalry drill hall (骑兵训练场) into an adventure destination in the heart of the city? You get Base Camp for overnight lock-ins, weekend retreats (隐居处) and summer camp.

    Inside out: Most of Base Camp is indoors, meaning the activities like climbing walls can be undertaken on winter's coldest days.

    Popular music in America is what every student likes. Students carry small radios with earphones and listen to music before class, after class, and at lunch. Students with cars buy large speakers and play the music loudly as they drive on the street.

    Adult drivers listen to music on the car radio as they drive to work. They also listen to the news about sports, the weather, and the life of American people. Most of the radio programs are music.

    Pop or popular music singers make much money. They make a CD or tape which radio stations use in many places. Once the popular singer is heard all over the country, young people buy his or her tapes. Some of the money from these tapes goes to the singer. Wherever the singer goes, all the young people want to meet him or her. Now the singer has become a national star.

    There are other kinds of music that are important to Americans. One is called folk music. It tells stories about the common life of Americans. Another is called western or country music. This is started by cowboys who would sing at night to the cows they were watching.

    I had about 10 minutes to exercise before I had to pick up my two older daughters from school yesterday. It was a busier day than usual for me with a couple of meetings besides my regular work.

    Years ago, I would have put off my workout and would have left things for the next day. But since it was a busy day as well, I knew that I may not have all that much time either. So, I picked up my kettle-bell (哑铃) and went to town for 4 minutes.

    See, 4 minutes, if that's all you've got, is enough to give your body a great fat-burning exercise. How did I get a killer workout in 4 minutes? I used a training workout discovered 10 years ago by a Japanese Sports Scientist called a TABATA.

    It includes 20-second periods of warm-up, followed by 10-second periods of rest and 4-minute straight exercise. How is a 4-minute exercise able to burn fat? It all depends on the quality of work you do. Not on the quantity. Here's how I did it yesterday.

    You should never forget your warm-up. A TABATA workout is 20 seconds of 2-arm Kettle-bell swings, 10 seconds rest, 20 seconds push-ups, and 10 seconds rest. You should do those 4 rounds. That's it. I was done in a total time of 8 minutes by the time and when I got to school my heart was still pumping pretty hard.

    A healthy body is needed for studying and working, and efficiency (效率) is the key to building a great body in the least amount (数量) of time possible and you can't get more efficient than a 4-minute workout.

    Few of us make money by losing sleep. But three graduate students at Brown University in Providence built a company around sleep deprivation(睡眠不足).

    Jason Donahue, Ben Rubin and Eric Shashoua were working late nights in Brown's business and engineering schools. They began thinking about ways to sleep better. They discovered they weren't alone in burning the midnight oil. Around 20% of Americans get less than six hours of rest a night.

    The friends imagined a smart alarm clock that could track how much time people spend in the most restorative(有恢复作用的) stages of the sleep cycle: REM (rapid eye movement) and deep sleep. What would it cost to design such a thing? Five years of research, 20 employees, $14 million and a whole lot of doubting from investors and scientists.

    Their company, Zeo, based in Newton, Mass, launched its product in June, 2009. The Zeo device uses a headband with tiny sensors(传感器) that scan your brain for signs of four sleep states-REM, light, deep and waking sleep. The smart alarm clock displays a graph of your sleep pattern and wakes you as you're not in REM sleep. In the morning you can upload the data to the company's Web site, and so track your sleep over time. Most of the feedback(反馈) comes in the form of Zeo's ZQ score showing how well you've slept.

    “Zeo allows people to unlock this black box of sleep,” says Dave Dickinson, a health-care CEO.

    Whether any of this actually improves sleep is up to the consumer, who will also need to make lifestyle changes like cutting out alcohol before bedtime or caffeine after 3 P.M.

    For now the company is selling Zeo online only. Dickinson also plans to spread it to countries such as Australia, where sleep deprivation approaches US levels.

    A campaign is being launched to encourage children to surrender 30 minutes of screen time a day to head for the great outdoors.

    The newly formed Wild Network—a collaboration of nearly 400 organizations—is attempting to attract youngsters away from television and computer screens to fields, woods and parks. Members of the network include the National Trust, RSPB, Play England and the NHS. Organizers say it is the UK's biggest ever campaign to reconnect children with nature and outdoor play, and claim it could help improve fitness, mental alertness and general well-being.

    A documentary film, Project Wild Thing, will forecast the launch at more than 50 cinemas across the UK from Friday. It looks at the increasing link between children and nature.

    Andy Simpson, chairman of the Wild Network, said, "The tragic truth is that kids have lost touch with nature and the outdoors in just one generation. Time spent outdoors is decreasing, roaming (漫步) ranges have fallen largely, activity levels are declining and the ability to identify common species has been lost."

    Suggestions on how to get more time in nature include collecting conkers (七叶树果), camping, snail racing, and observing autumn colour on trees.

    From January, the network will aim to make suggestions on how the government can do more to get children muddy and bright-eyed.

    This is not the first time the message of less screen time, more play has been brought up. Children in the 1980s were requested to do the same by the BBC TV series Why Don't You, which somewhat confusingly called on its viewers to "switch off the TV set and go to do something less boring instead".