Summer holidays are coming soon. Are you going to travel? If you plan to take a plane, you will have a healthy trip by following these suggestions:

I went to Grand Canyon (大峡谷) National Park in July 2012 for the firsttime and I knew I wanted to work there as a park ranger（管理员）. Park rangers protect the park's animals, plants, land, buildings, andpeople.

Now, as a park ranger forGrand Canyon National Park, I share the science, history and beauty of this parkwith thousands of visitors from around the world.

National parks are like outdoormuseums. Park rangers have all kinds of jobs, depending on where they work and whatthey studied during college. I teach school field trips（实地考察）, work at visitor centers and helppeople stay safe during their visit.

My favorite part of my jobis showing children their first look at the Grand Canyon during school field trips.Children are often amazed at the canyon's size and colors. Sometimes, they thinkit looks like a painting.

Being a park ranger requiresa lot of energy. I walk several miles and talk with hundreds of people each day.Park rangers must enjoy working with people and speaking in front of groups. Nearly5 million people visit Grand Canyon National Park every year.

Park rangers must also beprepared for any situation. Recently, I broke a traffic jam(堵塞). It was caused by a huge elk（麋鹿）standing in the road. Elks can become dangerous when they get scared,so I asked visitors to stop their cars and take pictures from far away. Believeit or not, I also help protect people from monkeys. It is not allowed to feed animalsin national parks. But sometimes, visitors try to feed monkeys.

Food waste is common in many schools. Students at Whitewater Middle School in the US once found 200 pounds (90. 7kg) of food had been thrown away after just one of their school's daily meals. They said it was both unpleasant and educational. 

A student said, "You don't realize how much food waste you're making till you see it. " To deal with this problem, Whitewater has added environmental science as a new school program this year. Teachers will lead students to do research about how food connects with the environment, poverty (贫穷) and people's health. 

Whitewater teachers make sure students know how their own eating habits are part of bigger problems. In environmental literature (文学) classes, students read books such as Fast Food Nation: The Dark Side of the All-American Meal. 

Teacher Lyman says that in language arts classes, students discuss why poor people often have less healthy food. Lyman says she wants students to ask themselves some basic questions: "What do we eat? What do we waste?

More and more Americans are going to work by bike. Do you know why more people are 1 bikes to work? We can answer the question in 2 ways. First, bikes don't need gasoline(汽油), so it takes less 3 to use them. Second, a bike doesn't 4 much space(空间), so it is 5 to find a place for it. And riding a bike is good for one's 6 . People often drive their 7 to offices or to shops, but now people think riding bikes is a good way of doing sports.

That's 8 more Americans are now going to work 9 bike, and they are 10 their own cars at home. 

Do you have a good sleep every night? March 21 is World Sleep Day. It's a good time to think about our sleeping habits (习惯) and get more sleep. Sleep is important (重要的) for our heath.

But today, many people have bad habits. They use their phones to talk with friends on Wechat (微信) or play games on bed. They get too excited before sleep. Some other people have too much stress (压力) from work. It makes them have bad sleep.

Losing (失去) one or two hours of sleep every night can make us tired or get ill. "If you don't get enough sleep at night, you may sleep in class. If you sleep, you don't learn anything," said Mary, a teacher from a middle school.

How much sleep do you need? For 12 to 15-year-old students, you need 8.5 to 9 hours a day. The best time to go to bed is 10:00-10:30 at night.

How to sleep well?

✧ Stop using your phone before sleep.

✧ Try to go to bed at the same time every day, even on weekends and holiday.

✧ Listen to beautiful music before you go to bed.