One day，Mr.Arnold was teaching a lesson，and things were going as normally as ever.He was explaining the story of mankind to his pupils.He told them that，in the beginning，men were nomads(游牧人)；they never stayed in the same place for very long.Instead，they would travel about，here and there，in search of food，wherever it was to be found. And when the food ran out，they would move off somewhere else.

He taught them about the invention of farming and keeping animals.This was an important discovery，because by learning to cultivate(耕作)the land，and care for animals，mankind would always have food steadily available.It also meant that people could remain living in one place，and this made it easier to set about tasks that would take a long while to complete，like building towns，cities，and all that were in them.All the children listening were attracted by this story，until Lucy jumped up：

    “And if that was so important and improved everything so much，why are we nomads all over again，Mr.Arnold？”

    Mr.Arnold didnt know what to say. Lucy was a very intelligent girl.He knew that she lived with her parents in a house，so she must know that her family were not nomads；so what did she mean?

“We have all become nomads again，” continued Lucy.“The other day，outside the city，they were cutting the forest down. A while ago a fisherman told me how they fish.Its the same with everyone：when theres no more forest left, the foresters go elsewhere，and when the fish run out, the fishermen move on.Thats what the nomads did，isnt it？”

The teacher nodded,thoughtfully. Really,Lucy was right. Mankind had turned into nomads. Instead of looking after the land in a way that we could be sure it would keep supplying our needs，we kept developing it until the land was bare.And then off we would go to the next place！The class spent the rest of the afternoon talking about what they could do to show how to be more civilized.

    The next day everyone attended class wearing a green T-­shirt，with a message that said，“I am not a nomad！”

    And，from then on，they set about showing that indeed they were not.Every time they knew they needed something，they made sure that they would get it using care and control.If they needed wood or paper，they would make sure that they got the recycled kind.They ordered their fish from fish farms，making sure that the fish they received were not too young and too small.They only used animals that were well cared for，and brought up on farms.

    And so，from their little town，those children managed to give up being nomads again，just as prehistoric men had done so many thousands of years ago.

    Aerial performer Jennifer Bricker was born without legs, but she never let it stop her.

    Wrapped in a loop of red silk hung from the ceiling Jennifer Bricker climbs and twists to the music. Her head hangs down and her strong arms let go as she balances on her back, high above the ground a move that's all the more daring because she has no legs.

    Jennifer was a few months old when she was adopted by Sharon and Gerald Bricker. She had big brown eyes, a bright smile, and huge amounts of energy. When a doctor advised her adoptive parents to carry her around in a kind of bucket, they refused.

    Jennifer soon learned to walk — and run — on her hands and bottom, and grew up fearlessly climbing trees and bouncing on the trampoline（蹦床） with her three older brothers. “My parents didn't treat me differently so I didn't grasp the concept that I was different. I knew I didn't have legs but that wasn't stopping me from doing the things I wanted to do.”

    At the age of three she was fitted with artificial legs, but she never really took to them — she moved more freely without.

    In 1996 the Olympic Games took place in Atlanta. Jennifer loved to watch the women's gymnastics team, and especially adored the 14-year-old Dominique Moceanu who competed for the US. When Moceanu and the women's team won gold, Jennifer decided she was going to be a gymnast, too. She took up power tumbling, which involves performing floor exercises down a runway. But Jennifer did not want any allowances to be made for her disability.

    At the age of 10 she took part in the Junior Olympics and by age 11 she was tumbling champion for the state of Illinois.

    Jennifer now travels the world as an inspirational speaker and acts as an aerial performer.

    The Broadcom MASTERS competition aims to find a balance between celebrating individual accomplishments and acknowledging that science seldom happens alone. The competition takes off when students from around the country are teamed up and have to solve a series of hands—on challenges in the spotlight.

    Nowadays, kids are fed with “the myth of the lone scientist”, so placing such challenges in the middle school period has a huge potential for impact. The focus on teambuilding skills gets students excited before more fears and stereotypes(成见)set in.

    The initial pool of qualified students comes from the participants in nation-wide science fairs. Those who score in the top 10％(about 10, 000 kids)have the qualification to apply. The judges select the top 300 young scientists, and that group is finally narrowed to 30 finalists.

    Selection at this stage is clearly an honor in itself, but it counts as step one for the finalists. They are then flown to Washington, D. C. and placed into teams of five for the hands-on part of the competition. Each team is made up of students with different talents and skills, including academic focus and experience.

    Unlike the science fairs, where most of the work takes place behind the scenes and students share a polished outcome, the hands-on challenges create a space where the work is the competition itself. The students take up a range of challenges in science, technology, engineering, math and so on. Each of the challenges will need the insight and skills of multiple team members.

    Judges observing the challenges aren't just looking for outcomes but also for leadership, teamwork and problem solving.

    The Broadcom MASTERS attracts increasing numbers of passionate and talented young people who are eager to take part in a program that helps them grow as scientists, engineers and inventors. It lets the students experience a sense of coming together with true peers. More importantly, it provides them with new skills to tackle future challenges.

    Once there were two mice. They were friends. One mouse lived in the country; the other mouse lived in the city. After many years the Country mouse saw the City mouse; he said, "Do come and see me at my house in the country." So the City mouse went. The City mouse said, "This food is not good, and your house is not good. Why do you live in a hole in the field? You should come and live in the city. You would live in a nice house made of stone. You would have nice food to eat. You must come and see me at my house in the city." The Country mouse went to the house of the City mouse. It was a very good house. Nice food was set ready for them to eat. But just as they began to eat they heard a great noise. The City mouse cried," Run! Run! The cat is coming!" They ran away quickly and hid. After some time they came out. When they came out, the Country mouse said. "I do not like living in the city. I like living in my hole in the field. For it is nicer to be poor and happy, than to be rich and afraid."

    We have heard some interesting ways that 5G wireless technology might change our lives in the future.

    5G, short for the 5th generation mobile communication technology, promises Internet speeds between 50 to 100 times faster than current 4G systems. While 5G is set to be used in some limited areas of America this year, much of the world is not expected to receive widely available service until 2023.

    One project in Britain, however, is already testing this superfast technology on an unlikely group of Internet users-cows. The project was developed by American technology company Cisco Systems. It also receives money from the British government. Cisco says the program seeks to explore the future of 5G connectivity in rural areas around the world.

    Testing areas were set up at farms in three rural areas of England. The cows are equipped with 5G-connected devices (装置) that link up to a robotic milking system, which uses sensors and machine learning to fully automate the process. System designers say technology takes over after a cow feels ready to be milked and walks toward an automatic gate. The device is designed to recognize each individual cow. It then positions equipment to the right body position for milking. During the process, machines release food for the cow as a reward.

    Other 5G technology tools include automated brushes that turn on when the cow rubs up against them. Sensors also control the amount of light to the cows' living areas depending on the weather. And, an automatic feeding system makes sure the animals always get enough to eat.

    Duncan Forbes, head of the project, told Reuters that the project shows the farm's cow operations can be greatly improved with 5G technology and that the experiment provides strong evidence that 5G technology can be widely used in the future, not just on farms in Britain, but in rural communities across the world.

Online jobs have opened the door for many people to earn a living (谋生) or make some extra money from the comfort of their homes.This includes teens as well.If you're looking for such a job, here are some choices you can consider.

Customer Service

If you are 16 years old and over, you have a chance to work with Uhaul as a customer service person.You just need to have a good pair of head－phones and high－speed Internet in order to do this job.Basic pay starts at $7.50 an hour.

Sell Items Online

Selling items online is one of the easiest ways to make quick cash.Teens can turn it into a good business by selling things on Bonanza.You need to start sorting through (分类) items at your home that are no longer being used and list them for sale.

Take Surveys

Another easy task teens can do to earn money is to take surveys online.You don't need any work experience to do this and can be as young as 13 years old to get started.Survey sites like VIP Voices，Swagbucks，Harris Poll, E－Poll, and Paid Viewpoint allow teens to start taking surveys for cash and gift cards.And your opinions should be expressed clearly in English.

Etsy

Do you love to make new things? You can open up an Etsy shop to share your works.Etsy is great for DIYers who can create new products.If you are under 18, you just need a parent who is willing to help manage your shop.