Mr Guo is a teacher from Xi'an．He asked his students to hand in their homework through a QR code （二维码）．"We spent an hour or two in class learning how to generate （使产生） the codes，and in the end everything gets easier，"said Guo．"When students finish the homework，they keep it on WeChat （微信）．Then，each student makes his own QR code and gives it to me．So I can check their work everywhere using my computer or telephone．"

    The QR codes can be sent to Mr Guo by email，QQ and WeChat．When Guo scans （扫描） his students'QR codes，their homework appears on his phone．He finds that their homework becomes more creative （创新的），with many pictures，music and even videos．

    Guo's students like the new way and think it is interesting．"We are living in the information age．Many students like to work with computers，which makes learning more fun．"said Tingting，a student of Guo's．

    "The paper is not easy to keep，but the code is easy to keep and share．"Guo said．" It is worth trying to use new technology in education．Education itself is a kind of creation．I don't want my students to fall behind the times．"

    However，some parents are worried．They are afraid that their children will spend too much time on computers and less time communicating with teachers．But in fact，it's unnecessary．Students still need to look up information in books and write it down when they do their homework．They only use the code when they hand in their work，which doesn't take them too much time．Also for teachers，it allows them to check the students'work at any time．And it's also an easy way to share homework with other students．

    Stephen Hawking was one of the most famous scientists in this century. He was born in 1942. He's a world well-known on space and time. Stephen is researching some very big questions, such as: How did the universe begin? How will it end?

Stephen was a student at Oxford University. He studied math and science. Then, at the age of twenty, he became sick. He was so young, but the doctors said to his family, “He has only two more years to live.” As a matter of fact, the doctors were wrong—- he didn't die. He can't walk now but he uses a wheelchair(轮椅). He can't feed himself and get in or out of bed himself. But he refused to give in to the condition. He talks with the help of a computer. After Oxford, Stephen went to Cambridge University. Three years later, in 1965, he became a doctor of philosophy(哲学).

    Because of his serious health problems, it was difficult for him to draw diagrams(图表)or to write. So he started to think in pictures. With this new way of thinking, he became one of the most famous scientists in the world. In 1991, he met the Pope(教皇) in Rome. They talked about his ideas. Then in 1998, he wrote his first important book, A Brief History of Time. It sold more than 5.5 million copies in 33 different languages. He was once invited to China, he impressed us with his self-confidence, humorous and witty(风趣的) conversation.