高一英语教案：Unit2 News media(第一课时)思维导图

Ⅲ. Teaching Time: Four periods

In ancient times the only way that men could send messages from village to village was on foot. When men learned to use the horse, communication became much quicker. However, compared to the modern world communication was still quite slow. Many parts of the world had no knowledge of events in other places. Later, the post was introduced and horse riders carried letters. This meant that communication was further improved. Horses drawn coaches could move people from town to town in quite a comfortable way. At the beginning of the last century the steam train was invented and for the first time really fast communication became possible. Not only could letters be sent easily from one part of a country to another, but travel was made easy, too. At about the same time, steam ships helped communication between countries.

The invention of the telegraph in the middle of the last century further increased the speed at which messages could be sent. In this system electrical signals, in code, are sent along metal wires. These signals travel so fast that they could go nearly eight times round the world in one second. A special device is needed to send the code. At the other end another device is used in order to receive the code. By this method messages can be sent over distances of several hundred kilometres. With the invention of the telephone the human voice could be sent over long distances. Because of this the telephone system replaced the telegraph for quick communication over long distances. The telegraph is still used, however, by newspapers in order to send news and for other purposes too.