Have you ever rubbed your hands together when they get cold? Why do we do that? We do that for friction. Friction happens when two things that aren't very smooth rub together to make heat energy. The faster you rub two things together, the more friction (and heat) you can make. Let's discover friction!

What is your favorite color? Ask famous persons like Cate Blanchett, Scarlett Johnson, and Bono (singer for the band U2), and maybe they will say “green.” That's not because these artists like the color green best. Instead, they are interested in green fashion.

       Green fashion is about making (and wearing) clothes that are good for humans, animals, and the Earth. In the past, green fashion made people think of ugly clothes. But today, green fashion is different. It is about looking good and caring about the Earth and other people. You can have interesting clothes and be green.

Around the world, green fashion is becoming popular. For example, the U.K. company People Tree sells men's and women's clothing and accessories(配搭物). They are made from natural fabrics(织物) like cotton and wool. Workers who make the clothes are from countries like Kenya(肯尼亚), and Bangladesh(孟加拉国). People Tree pays the men and women good money for the clothes they make.

Singer Bono and his wife also started a clothing company called EDUN. When the clothes are sold, EDUN uses most of the money to help people around the world.

    There are all kinds of horses in the world. But one of them you can't ride. It doesn't live on land, but in the sea. Its head looks like the head of a horse .So people call it a "sea horse." In fact, The sea horse is a small fish. It likes to live in warm water. A sea horse always stands up in the water when it swims.

    The mother sea horses give eggs, but they put the eggs inside   father's body to keep them safe in its pouch until they hatch()孵化. When the eggs are hatched after 40 to 50 days, the baby sea horses swim away.

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    Some days, don't you think, "Wouldn't it be nice if the laundry would just do itself?” Self-cleaning clothes may sound crazy. But Australian researchers have found a way to make something like this possible!

    A team at RMIT University in Melbourne, Australia, found a way to put special nanostructures (纳米结构) into clothing, which can then clean the clothes. When sunlight hits the nanostructures, they break down the dirt and stains (污渍) that don't belong on your clothes.

    The nanostructures don't break down the actual clothing because cotton and the other clothing materials are too strong to be broken down. According to CNN, the researchers cover the clothing in a solution made of silver and copper (铜) nanostructures. All it takes is 40 minutes of sunlight and your clothes will look as good as new.

    So if you spill on yourself during lunch, you can step outside for a walk, and it will be clean by the time you go inside. It not only makes your life easier, but it can also be good for the environment.

    According to the US Department of Energy, the average load of laundry uses about 25 gallons (about 94 liters) of water. Water is a very important resource, so using less of it to wash clothes is better for the environment. But one of the scientists at RMIT University knows more needs to be done.

    “There's more work to do before we can start throwing out our washing machines,” said Dr Rajesh Ramanathan, “but this is a strong foundation (基础).”

    So what's the next step? Ramanathan wants to either start selling the solution by itself or convincing (说服) clothing makers to treat the clothing with the solution while clothes are being made.

    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."