Have you ever stood beside the ocean and stared at the waves (波浪)? The way they move is changing! Nothing is more peaceful than watching the movement of water.

    Every ocean has waves. Unless you are lucky enough to live by the sea, though, you probably can't watch the waves very often. How would you like to have your own wave machine? Making one is easy and a lot of fun.

    Now that you have made your ocean, put your bottle on its side. Wait a minute. The water win be on the bottom. The oil and paint thinner mixture will be on the top. Now tip (倾斜) the bottle back and forth (反复来回) and watch the waves.

    The Earth is about 4, 600 million years old Man lives on the Earth for only 35, 000 years. But we change our Earth in many ways. Many things we do are good, but some are not good for the Earth.

    Water pollution

    A lot of people, birds and fish die each day because of water pollution. Factories pollute the water. As a result (因此), the water in many rivers and lakes is now very dirty.

    Air pollution

    In big cities, factories, cars and buses are the main causes of air pollution. Many people in cities now have health problems. For example, Mexico City used to be a beautiful sunny capital, but today there are many clouds in the sky. And many people get ill because of the polluted air.

    Soil (土壤) pollution

    In order to have a better harvest (收获), some of the farmers use chemicals too much in their fields. That's bad for the soil.

    Hope for the future

    These problems are very serious for our future, so all of us should do something to protect the environment. If we can stop pollution, our Earth will become more and more beautiful.

    We all know that many women like to wear dresses. They enjoy many kinds of colourful and popular dresses. But have you ever heard of a 4D dress?

    Jessica Rosenkrantz in the USA used 3D printing technology to make a very special and new dress. It will help with the problems of different styles for women's dresses.

    The dress maker called the special dress a "4D dress". It is like the fabric(织物). It can turn into different kinds of shapes.

    The company, in Massachusetts, the USA, also made a smartphone and an app(应用软件). They can help women to control their dresses. If women use the phone and the app, they can change the colour, the style and many other things of the dresses. Isn't it very interesting?

    When she talked about her work, Jessica said, "There will be many more changeable dresses for women in the future. I am interested in making them too. I can't wait to make different kinds of new dresses for women."

    There are lots of objects that we see in the sky. During the day we see the sun. After the sunset in the evening, we see mostly the stars. Not all the lights in the sky that we see are really stars.

    Of course, we see the moon. Some of the other lights in the sky are planets. Planets revolve (转动) around the sun like earth does.

    Once in a while someone will see what they call a shooting star.

    Shooting star looks like a star that is moving quickly across the sky. Some people believe that seeing a shooting star will bring them good luck. It's hard to find shooting star because they disappear fast.

    The correct name for a shooting star is meteor. Besides very large objects like stars, planets and moons, space has lots of little objects. These can be rocks in space left over from old planets.

    These objects can even be as small as dust. These objects are called meteorites(陨石).

    When a meteorite gets close to the earth, it gets pulled towards the earth by gravity. Earth is surrounded by atmosphere. Atmosphere is made up of air and clouds. A meteorite blows up in the earth's atmosphere. This makes the short bright moving light in the night sky. A meteorite thus turns into a meteor.