As young students gain independence, they can take on science and engineering projects that require more special knowledge. The followings are the best educational toys for middle school students.

    Terraforming Mars

    The goal of the Terraforming Mars board game is to make the Red Planet fit of human habitation. Players, representing a person sent to the planet to warm it create oceans and build up the oxygen levels, compete for victory points awarded for building cities or introducing animals. The goals are based on real science—for example, players must found greenhouse gas production to warm the planet.

    Recommended ages: 12 and up

    Price: $69.99

    DIY Cell Phone Equipment

    Are you kids begging you for the latest for the latest iPhone? Tell them to build up their own. DIY Cell Phone Equipment will teach young teens about the technology behind their beloved mobile equipment. Kids can turn this Phone equipment into a real working phone.

    Recommended ages: 12 and up

    Price: $58.99

    OWI: 14-in-1 Solar Robot

    Kids can experience 14 different robotic models with this solar robot. The robot can move on land and water, and there are two skill levels, which means more experienced builders will still be challenged. The robot is powered by the sun, so you don't have to buy batteries（电池）.

    Recommended ages: 12 to 15

    Price: $24.99

    Compound Microscope

    Compound Microscope is great for home or classroom explorations. It helps kids get an eyeful of solid samples, such as insects, coins and plants. The microscope also comes with a microtome, dyes, test tubes, a handbook and cleaning tools.

    Recommended ages: 12 and up

    Price: $89.95

    Chinese scientists called on all over the country to fight against serious water pollution in China yesterday.Following days of heavy haze(雾霾)that influenced most parts of China earlier this year polluted water is becoming another big worry among people on popular social Internet

    Websites have called for cutting down water pollution in necessary ways.

    “We should not only protect water,but also pay attention to water pollution,”said Xue Manzi,a well-known investor(投资人)on Sina Weibo.“Dead pigs are found in rivers and waster is poured into rivers and underground.”said Xue.The Huangpu River provider 22 percent of Shanghai's drinking water.But earlier this momth,thousands of dead pigs were found in it.This made people scared and worried,although local government tried to showthat the water was safe.

    In February,some factories in Weifang in Shandong had put waste water underground,polluting the local drinking water.“Clean water and air are necessary for people to live. A responsible government will strictly protect the environment from being polluted,”said a microblogger.

    Isn't it time for us to have a better thinking about our living environment?Do we want to kill ourselves by serious pollution? All the companies should have a serious sense of responsibility.The health of people is far more important than money!

聚合氯化铝铁Fe_aAl_b（OH）_cCl_dm是一种性能优良的无机高分子絮凝剂，在净水行业得到广泛应用．