When I was a university teacher in Ningbo, I told my students that it would be wise to keep their smartphones in their backpacks. They were young adults. I didn't want to take their phones， nor could I shout at them. You can guess what happened.

    Some students were polite, using their phones between activities. Others would rudely text their friends during lessons, sometimes even while I talked to them. One young woman, K, openly played a game at her desk with earphones!

    Why did such a situation appear? I began to think my class was boring (probably true!) and that my students hated me (I could understand). But what could I do? I couldn't fail every student. Maybe I was just a boring teacher.

    With all the recent talk about banning(禁止) smartphones at schools, you might think I'm in favor. I'm actually not so sure. This technology isn't going away. Teachers probably need to change as much as students.

    I designed activities to let them use pens and paper, and moving around the room to talk to classmates. It kind of worked! I also found ways to use their phones. Things like research, translation and creative projects. I found that my students worked hardest on these activities.

Phones might not be the biggest problem. Once, walking at school, I saw K standing alone in the dark. I could see her face, lit up by her mobile game. Maybe smart phone addiction (上瘾) at school is a sign of loneliness or a boring teacher.

These days, more and more people like the "city walk" around China. The city walk is a kind of city tour coming from the UK. It means tourists follow a planned route（路线）working deeply on the city's history and culture. During the traditional kind of travel, people need to follow a group of people. But city walk routes are special for every tourist. People probably choose a route on their own and move on foot without a purpose. They can also talk with locals（当地人）and taste local food on their way. 

City walkers may be tourists from other places or local young people. For tourists, by taking part in a city walk, they can learn the city's history and culture. For the local young people, they may spend weekends knowing more about their living places. And they even share their routes and places online. So more people get interested in their cities and come to visit them. 

Now the city walk is very hot. However, we also find that to make money, some travel agencies（旅行社）may make some routes without understanding the culture and history of a city. That will make tourists lose interest in the city walk. What's more, many young people spend much time taking photos to just show themselves online. 

Without classes and exams, the summer vacation is an ideal time for Australian kids. For me, Nancy, it means much more than not going to school. It is also a golden chance to spend time with my family because I have little time with them during the school year.

Last summer vacation I travelled with my family to the Hawkes bury River in Western Sydney. It was one of the most unforgettable summer vacations in my life.

Staying by the river helps us escape from the hot weather and noise of the city. Every day, my family and I got up early to go swimming in the cool water. In the morning, we all took part in a big game. We enjoyed water— skiing, wakeboarding(尾波滑水) and other activities. These activities made our family feel closer.

In the warm afternoon, we peacefully read books on hammocks hung among trees by the river. The days always ended with a campfire. We sat around the fire, talking and laughing.

The river is a perfect place for people to forget about all the stresses(压力) of life and simply enjoy the moment. To me, it is the best place to spend time together with my family. I can't help thinking about those days again and again although so many months has passed.

 For years, scientists have been researching how exposing(暴露) humans to nature may improve their physical and mental health. People are encouraged to visit forests and grow houseplants. Now researchers are also testing whether we can get some of the same benefits from experiencing nature in VR(虚拟现实). 

 Scientists are trying to understand what exactly about nature makes a real difference in health results. One tool that might help is VR, says Hector Alvarez, who wanted to find out if simply seeing nature can relax people. In an experiment, VR allowed him to expose people to the visual(视觉的) experience of nature while controlling temperature, light and air pollution. He is now preparing to publish his research. 

 People can feel safe faster in environments with lots of plants, Hector explains. "That's why I was interested in VR. If it is right that we feel safe faster in nature, it should bring your stress levels down. "

 So far, Hector says, research shows there are some health improvements by experiencing nature in VR. However, they are smaller than those got in the real nature. 

 Gretchen Daily is an environmental scientist at Stanford University. She agrees at parts of this research, especially in situations without nature. But in the long term, connection with nature in the real world can not be replaced. To some degree, Gretchen worries that the idea might take off that VR can replace the real thing. "If that's taken very far, that' ll be really harmful overall because the real thing is necessary in so many ways, " she says. "We just cannot live on a dead planet. "