Five hundred years ago, potatoes grew in South America. They were an important food for the people who lived in these high mountains. In other parts of the world, however, people didn't know about potatoes.

    The Spanish came to South America in the 1500s. They learned of potatoes and took some back to Spain. By 1570, people grew white potatoes in parts of Spain. By 1580, people in Italy were also growing potatoes.

    From Spain, potatoes travelled to France. In France, however, people were afraid to eat this new vegetable. They thought it was bad for health. Then the King of France tried to make his people eat potatoes. But for many years, the French still refused to eat potatoes.

    Potatoes reached England in a different way. In 1586, the English explorer(探险家) Drake stopped in Colombia. There he probably picked up some potatoes and took them back to England. At first, the English refused to eat potatoes, too. They used potatoes to feed their pigs and chickens.

    From England, the potato travelled to Ireland. The potato grew well in the poor soil of Ireland and soon it was an important food for the people in Ireland.

    In the early 1700s, Irish people brought potatoes to North America. By 1750, many people in New England were growing and eating potatoes.

    Thousands of years ago,in the south of ancient China,there lived Shennong,a man who had an ox head and human body.Seeing that local people were suffering from disease,he built ladders and houses on a high mountain to store hundreds of medical plants.To remember him,people named the place shennongjia.

    The legend(传说）makes Shennongjia in Hubei an inciting place for tourists.Traveling there is a unique experience,as you can see sceneries of the four seasons from different altitudes(海拔）.“When the bottom of the mountain is summer,the top is spring and while the foothill is autumn,the top is covered with ice,”local people say of the special climate of Shennongjia.

    Shennongjia is also home to 5,000 species of animals and plants.Many animals in danger live there,such as the golden monkey,the clouded leopard and the Asian black bear.

    One interesting and mysterious(奇妙的）thing about Shennongjia is its legend of wild men.Some people once claimed that they saw big prints or big-foot creatures.Yet so far,scientists haven't proved it is true and some say they are just bears.

    The beautiful place has recently received a new title.On July 17,2016,Shennongjia Forestry District was added to United Nations World Heritage list as a natural site.Chins now has 50 world heritage sites(遗址），second only to Italy in the world.

    Have you ever paid attention to the Air Quality Index (空气质量指标) or AQI reported in the newspaper? The AQI helps us understand what the air quality around us means to our health. The AQI uses colors, numbers and words to tell us about the air. Let's see what these colors and numbers mean.

    DNA is the whole" map" of the human body. It is something that all humans have, and it tells the body what to do. DNA is the reason that we look like our parents, because we get some of their DNA to make our own.

    People have been trying to understand the human body for a long time. In 1860, Mr. Mendel discovered why we look the same as other people in our family. It is because of small things called "genes" (基因)in our body. In 1953, two scientists, Watson and Crick, found out that genes are really messages. They're written in the DNA with a special language.

    In 1961, another two scientists found the first" word" that they could understand in that language. It shows how DNA tells the cell(细胞)to build its parts. So far, scientists have found all the words in the DNA map, but we still don't understand what they all do. By understanding what just one" word" means, we can help to save people from several illnesses. So the more we understand, the more doctors will be able to do.

    Most people hope that this can help to make better medicine to help sick people. Other people worry that when we learn more" word" and find out more information, we will use it in the wrong way. Just to make people more attractive, or stop sick people getting jobs.

    This week is Computer Science Education Week. During the week, students around the world will be taking part in an "Hour of Code" and learning a little about programming computers. This year, there will be more than 200.000 events in over 180 countries.

    The U.S. Congress first created Computer Science Education Week in 2009 to remember Grace Hopper, one of the women who played an important part in the early days of computers.

    Hadi Partovi came up with the idea of the Hour of Code. He thinks coding is an important skill and that it's important for schools to teach computer science. He started the Hour of Code in 2013 because he was worried that computer science was not a big part of what schools taught in most states.

    To spread his idea, he got the help from many famous people. Some were famous for working with computers, like Bill Gates. Others were famous in other areas. Mr. Partovi got a lot of money for his idea from big companies like Facebook. Google, and Microsoft.

    Students who take part in the Hour of Code complete a short coding challenge that is broken down into small, simple steps. The challenge is supposed to take about an hour in all.

    To raise the interest of students, the challenges are often tied in with popular movies or games. For example, challenges have been built around Angry Birds. Mine Craft. Frozen. and Star Wars—One test of the program's success is whether students keep going once the time is up. It turns out that many of them do. Last year, teachers reported that 92% of their students coded for more than an hour.