The science of physics today is as current as the morning newspaper. Indeed, as a result of new advances in physics and their rapid application to inventions designed to satisfy man's wants,the world itself has been changing rapidly. Space technology, industrial technology, and the technology of the home, the farm, the office, the bank, and the department store have all been revolutionized.

Clearly, every grown-up today would understand the world he lives in much better if he knew something about physics. Whether it be Congress(美国国会)voting huge sums of money for warships, space exploration, or atomic energy; the office staff learning to use a new computers; Son Bobby wanting to know about going to the moon; or the housewife learning to operate a electric stove, physics seems to be everywhere.

Teachers in thousands of schoolrooms in America are trying to communicate some of the excitement and importance of these new developments to their students. They know that some of their eager student will someday be scientists and will themselves   then contribute to the development of new knowledge or its application to new things.

But in any case, they can be sure that if they bring a knowledge of science (any science) to their students in meaningful and stimulating ways, they have contributed much to helping each one live a more meaningful life.

Like all big cities, Paris has a traffic problem: lots of cars. lots of traffic jams and lots of pollution from exhaust fumes(废气). So the city began a scheme(计划)to improve the situation.

Under the Velib scheme ('Velib' comes from velo liberte, or 'bicycle freedom') people can take a bicycle, use it for as long as they want, and then leave it at the same or another bicycle station. The first half-hour-on the bike is free, but if you don't return it after 30 minutes, you have to pay. But it's only € 1 a day or € 29 a year! The bicycles are heavy (25kg), and they are all grey and have baskets. There are about 20,000 of them in the city, and around 1,450 bicycle stations. So there are a lot more Velib stations than the 298 subway stations!

Paris is not the first city to have a scheme like this. But not everybody thinks it's a great idea. One Parisian said. “These bicycles are only for short journeys. If people want to travel across the city, they won't use a bicycle-they'll still use their cars.”

A city spokesman said, “The bicycle scheme won't solve all our traffic problems, of course. But it might help reduce air pollution. Traffic, together with factory fumes, is a big problem. There aren't any simple answers to traffic problems and pollution in cities. But unless we do something now, there will be more traffic jams and temperatures will continue to rise, so the problems in our environment will get worse. The bikes might help people to lead a healthier life, too. “

Students at Empire High School started class with no text books-but it wasn't because of money problems.

Instead, the school gave iBbooks-laptop computers to each of its 340 students, becoming one of the first US public schools to stop printed textbooks.

School officials believe that the electronic materials will make students enjoy learning more Empire High School was designed to have a textbook-free environment.

Students at Empire High School get the materials over the school's Internet network. The school has a central control system that limits what can be downloaded at the school.

“Students can hand in homework online. We have a web program that helps to check if you copy from others,” the headmaster Baker said.

In addition to offering up-to-date information, teachers can make the lessons more enjoyable. For example, lessons in history can include links to a person's daily life, his ideas, his discovery, and so on.

Social studies teacher Jeremy Gypton said the change was easier than expected. Gypton said he assigned reading based on websites, used online groups and message boards to keep the students connected. And he also asked them to comment on each other's work.

Julian Tarazon, a new student, said that it was kind of hard at first, because you had to put things in folders(文件夹). But after a couple of days, you got used to it. Another student Morgan Northcutt said the computer system had made it easier to do homework.

The school isn't completely paperless, however. It has a library, and students can read books in it.

“We're not trying to get rid of book,” Baker said. “We love books.”

Summer is hot. One of the best ways to cool off on a hot summer day is to jump into a swimming pool. Swimming is great exercise, and .trip to a pool or beach is a good way to have fun with friends. But swimming can also be dangerous, so it's important to stay safe as you do it.     11    

Swim only in areas set for swimming.

Don't swim unless there is a lifeguard on duty. If you're on a beach near the ocean, this is especially important. In some places, fast currents(急流)can sweep swimmers away without warning.     12    

Be careful when diving into the water headfirst.

    13    In natural water, don't dive unless you know that the water is deep enough. Or you could hit your head on the bottom, causing injury or death.

Make sure you have a partner with you.

Nobody knows what will happen while you swimming.     14    In this situation, a few seconds can make a big difference.

    15    

Kids who don't know how to swim should wear life jackets. But by themselves they are not enough, so an adult should always be present. If you have a pool at home, put a fence around it in case children fall in. And if a child disappears, check the pool first.