A 17-year-old boy, caught sending text messages in class, was recently sent to the vice principal's office at Millwood High School in Halifax, Nova Scotia. The vice principal, Steve Gallagher, told the boy he needed to focus on the teacher, not his cellphone. The boy listened politely and nodded, and that's when Mr. Gallagher noticed the student's fingers moving on his lap. He was texting while being scolded for texting. “It was a subconscious act,” says Mr. Gallagher, who took the phone away. “Young people today are connected socially from the moment they open their eyes in the morning until they close their eyes at night. It's compulsive.”

    A study this year by psychology students at Covenant College in Lookout Mountain, Ga., found that the more time young people spend on Facebook, the more likely they are to have lower grades and weaker study habits. Heavy Facebook users show signs of being more sociable, but they are also more likely to be anxious, hostile or depressed. (Doctors, meanwhile, are now blaming addictions to 'night texting' for disturbing the sleep patterns of teens.)

    Almost a quarter of today's teens check Facebook more than 10 times a day, according to a 2009 survey by Common Sense Media, a nonprofit group that monitors media's impact on families. Will these young people get rid of this habit once they enter the work force, or will employers come to see texting and 'social-network checking' as accepted parts of the workday?

    Think back. When today's older workers were in their 20s, they might have taken a break on the job to call friends and make after-work plans. In those earlier eras, companies discouraged non-business-related calls, and someone who made personal calls all day risked being fired. It was impossible to imagine the constant back-and-forth texting that defines interactions among young people today.

    Educators are also being asked by parents, students and educational strategists to reconsider their rules. “In past generations, students got in trouble for passing notes in class. Now students are skilled at texting with their phones still in their pockets,” says 40-year-old Mr. Gallagher, the vice principal, “and they're able to communicate with someone one floor down and three rows over. Students are just fundamentally different today. They will take suspensions rather than give up their phones.”

    I often dreamed about Pisa when I was a boy. I read about the famous building called the Leaning Towers of Pisa(比萨斜塔）. But when I read the word Pisa, I was thinking of pizza. I thought this tower must be the best place to buy pizza in the world.

    Many years later, I finally saw the Leaning Tower. I knew then that it was Pisa and no pizza and that the tower got its name because it really did lean to one side. Some people want to try to fix it. They are afraid that it may fall over and they don't want it to lean over the city.

    I don't think it a good idea to try to fix it. The tower probably will not fall down. It's 600 years old. Why should anything happen to it now? And, if you ask me, I like what it looks like. It seems to say nothing is perfect. Imperfect things may be more interesting. Why is it so famous? There are many other older, more beautiful towers in Italy but Pisa tower is the most famous.

    Since many of you are planning to study at a college or university in the future, you may be curious to know what your future study will be like. This is the question I want to discuss with you today.

    First, let's talk about what your weekly timetable will look like. No matter what your major may be, you can expect to spend between four and six hours a week for each class attending lecture. Lectures are usually in very large rooms because some courses such as Introduction to Sociology or Economics often have as many as two or three hundred students, especially at large universities. In lectures, it's very important for you to take notes on what the professor says because the information in a lecture is often different from that in your textbooks. Also, you can expect to have exam questions based on the lectures. So it isn't enough to just read your textbooks; you have to attend lectures as well. In a typical week, you will also have a couple of hours of discussion for every class you take. The discussion part is a small group meeting usually with fewer than thirty students where you can ask questions about the lectures, the reading, and the homework. In large universities, graduate students called teaching assistants, usually direct discussion parts

    If your major is chemistry, or physics, or another science, you'll also have to spend several hours a week in the lab doing experiments. This means that science majors spend more time in the classroom than non-science majors do. On the other hand, people who major in subjects like literature or history usually have to read and write more than science majors do.

    Reading can be a social activity. Think of the people who belong to book groups. They choose books to read and then meet to discuss them. Now, the website Book Crossing.com turns the page on the traditional idea of a book group.

    Members go on the site and register the books they own and would like to share. Book Crossing provides an identification number to stick inside the book. Then the person leaves it in a public lace hoping that the book will have an adventure, traveling far and wide with each new reader who finds it.

    Bruce Pederson, the managing director of BookCrossing, says, "The two things that change your life are the people you meet and books you read. BookCrossing combines both."

    Members leave books on park benches and buses, in train stations and coffee shops. Whoever finds their book will go to the site and record where they found it.

    People who find a book can also leave a journal entry describing what they thought of it. E-mails are then sent to the BookCrossing to keep them updated about where their books have been found. Bruce peterson says the idea is for people not to be selfish by keeping a book to gather dust on a shelf at home.

    BookCrossing is part of a trend among people who want to get back to the "real" and not the virtual(虚拟). The site now has more than one million members in more than one hundred thirty-five countries.

A kind of blue dye (颜料) called folium had been widely used to paint pictures on the pages of manuscripts (手稿) created in the Middle Ages. But long ago, this watercolor fell out of use.

"Manuscripts are an important part of the cultural works of art in the Middle Ages," said scientist Maria in an email to CNN. "Color is a basic feature of these manuscripts. To let ancient manuscripts. keep a good condition for future generations, we sometimes need to repaint their inside pictures through the ancient dye — like folium — that was once used in these manuscripts. But everyone who knew how to prepare folium had died long ago. So 'I led a team to study this dye."

Her team turned to books from the 1400s and found one that described the plant that was its source. It is a tiny plant with silvery-green leaves. Days later, the scientists reached a village in south Portugal, where nobody knew this little plant. However, after carefully going through a plenty of different plants growing there, the scientists finally raked out the plant they wanted and brought some back to their laboratory.

Back in the lab, the scientists produced the dye with the help of an ancient text on colors. The text has clearly described the ways to make it. "It's cool to have done that work of looking in the historical records and traveling back in time," says Casadio, who was not part of this study. It recreates an ancient process. By making the dye, the scientists could study its chemistry without experimenting on priceless delicate (易损的)  works of art, she points out.

Now, the researchers don't know the dye's stability(稳定性)and its ability against the environment that may wear and break it down over time. "To know such information is necessary if we desire to make these colors last long enough," Maria said. "So our study will continue."