Television

Television is one of the greatest technological inventions of the 20th century. A Scottish man called John Logie Baird invented it. Inventors in the USA and Europe were working on electronic television systems but Baird used a mechanical system. In 1925, he was able to send the first black and white picture-of head of a doll-from one end of his flat to the other. He then used a local office boy, not the doll, and this teenager was the first person ever to appear on TV. 

More and more people had televisions after the Second World War. Colour TV began in the USA in the 1940s but only a small number of people had colour television in their houses. They were very expensive. In Britain and the USA, the first regular colour TV programmes only began in 1967.
Now, in 21st century, we have digital television. TV has changed a lot since the face of a boy appeared on TV in John Logie Baird's flat!

The Zipper

The zipper is a wonderful invention. How did people ever live without zippers? They are very common, so we forget that they are wonderful. They are very strong, but they open and close very easily. They come in many colors and sizes. In the 1890s, people in the United States wore high shoes with a long row of buttons. Clothes often had rows of buttons, too.. People wished that clothes were easier to put on and take off. 

A zipper has three parts: 1) There are dozens of metal or plastic hooks (called teeth) on two rows.
2)These hooks are fastened to two strips of cloth. The cloth strips are flexible. The bend easily.
3) A fastener slides along and joins the hooks together. When it slides the other way, it takes the hooks apart.
Dr. Sundback put the hooks on strips of cloth. The cloth hold all the hooks in place. They don't come apart very easily. This solved the problem of the first zippers.

Tarahumara Foot Races

The Tarahumara live in the mountains in the state of Chihuahua in northern Mexico. This is an are of high mountains and deep tropical valleys. It sometimes snows in the mountains in winter. There are not many roads. The Tarahumara walk wherever they need to go. They carry heavy baskets on their backs. Perhaps this is why the Trahumara can run many kilometres without getting tired, They are excellent runners, and they like to organize races.

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When the men race, they kick a wooden ball ahead of them while they run. The women's race are similar except that the women do not kick a ball.
The Tarahumara play integer Gaines abed sorts, Cuneiform they are famous because they can run so fast and so far.

The Postage Stamp

Before the invention of the postage stamp, it was difficult to send a letter to another country. The sender paid for the letter to travel in his or her own country. Then the person in the other country paid for the rest of the trip. If a letter crossed several countries, the problem was worse. Rowland Hill, a British teacher, had the idea of a postage tamp with glue on the back. The British post office made the first stamps in 1840. They were the Penny Black and the Twopence Blue. A person bought a stamp and put it on a letter, The post office delivered the letter. When people received letters they didn't have to pay anything. The postage was prepaid. Postage stamps became popular in Great Britain immediately. Other countries started making their own postage stamps very quickly.

The History of Money

Today,currency is a mixture of coins and paper money. But it wasn't always that way. Before people had metal coins and paper bills, they used a lot of unusual things for money. In one part of the world, for example, people used sharks' teeth for money. In some places, brightly colored feathers and rare seashells were money. People in one area even used the hair from elephant's tails for money. No one knows for sure when people started using metal coins for money. The oldest coins are over 2.500 years old, so we know that people used coins a very long time ago. At first, people used precious metals, such as gold and silver, to make coins. They stamped the shape of a person or animal on each coin to indicate its value. In the 13th century, people in China used iron coins for they currency. These coins weren't worth very much, and people had to use many of them to buy things. Because it was inconvenient to carry so many of these coins, the government started making paper receipts. People took these receipts to banks and traded them for coins. This was the first example of paper money.