Reducing the amount of sleep affects students' performance at school. An American study asked schoolteachers to look at the effects of sleep restriction（限制） on children between six and twelve years of age. The teachers found that children who stayed up late had trouble thinking clearly and had more learning problems.

    {#blank#}1{#/blank#} Doctor Fallone now works at the Forest Institute of Professional Psychology in Springfield, Missouri. He presented the results last month at a science reporter conference in Washington, D. C. The Publication Sleep also reported the findings.

    The teachers were asked to complete weekly performance reports on seventy-four schoolchildren. The study lasted three weeks. During that period, Doctor Fallone and his team controlled the amount of sleep the children received.

    {#blank#}2{#/blank#} During another week, every child was kept awake later than normal. Each night, the youngest boys and girls had less than eight hours of sleep. The older ones were limited to six and a half hours. During the final week of the study, each child received no less than ten hours of sleep a night.

    The teachers were not told about how much sleep the students received. The study found that students who received eight hours or less had the most difficulty remembering old information. {#blank#}3{#/blank#}

    The study did not find that sleep restriction caused hyperactivity(极度活跃) in the children. {#blank#}4{#/blank#}

    Doctor Fall one said that the results provided experts and parents with a clear message: {#blank#}5{#/blank#}

    When I was about 12, I had an enemy, a girl who liked to point out my shortcomings (缺点). Wee k by week her list grew: I was very thin, I wasn't a good student, I talked too much, I was too proud, and so on. I tried to hear all this as long as I could. At last, I became very angry. I ran to my father with tears in my eyes.

    He listened to me quietly, then he asked. “Are the things she says true or not? Janet, didn't you ever wonder what you're really like ? Well, you now have that girl's opinion. Go and make a list of everything she said and mark the points that are true. Pay no attention to the other things she said.”

    I did as he told me. To my great surprise, I discovered that about half the things were true. Some of them I couldn't change (like being very thin), but a good number I could—and suddenly I wanted to change. For the first time I went to a fairly clear picture of myself.

    I brought the list back to Daddy. He refused to take it. “That's just for you,” he said. “You know better than anyone else the truth about yourself. But you have to learn to listen, not just close your ears in anger and feeling hurt. When something said about you is true, you'll find it will be of help to you. Our world is full of people who think they know your duty. Don't shut your ears. Listen to them all, but hear the truth and do what you know is the right thing to do.”

    Daddy's advice has returned to me at many important moments. In my life, I've never had a better piece of advice.

    Have you heard of the following people? Maybe yes, maybe no. But they may be an inspiration for you.

    The Tree Lady

    Kate Sessions was an American botanist and landscape architect closely associated with San Diego, California. After becoming the first woman to graduate from the University of California, Berkeley, she took a job as a teacher far south in the dry desert town of San Diego. Kate decided that San Diego needed trees more than anything else. Therefore, this young woman single-handedly started a movement transforming the town into the leafy, garden-filled place as it is today.

    The Snowflake(雪花) Man

    Wilson Bentley is one of the first known photographers of snowflakes. His enthusiasm for taking photos began from his boyhood and was often misunderstood in his time, but his determination revealed two important truths: no two snowflakes are alike; and each is surprisingly beautiful. In 1931, he worked with William J. Humphreys of the U.S. Weather Bureau to publish Snow Crystals, a book containing 2500 photographs.

    The Father of His Country

    By the late 1760s, George Washington had experienced firsthand the effects of rising taxes imposed (征收) on American colonists by the British, and came to believe that it was in the best interests of the colonists to declare independence from England. During the American War of Independence, he led the colonial forces to victory. In 1878, he was elected president of the Convention that wrote the U.S. Constitution. Two years later, Washington became American's first president. His retirement from office after two terms established a tradition that lasted until 1940, when Franklin Delano Roosevelt won a third term. The 22^nd Amendment (1951) now limits the president to two elected terms.

    There's a new frontier (新领域) in 3D printing that's beginning to come into focus: food. Recent development has made possible machines that print, cook, and serve foods on a mass scale. And the industry isn't stopping there.

    Food production

    With a 3D printer, a cook can print complicated (复杂的) chocolate sculptures and beautiful pieces for decoration on a wedding cake. Not everybody can do that—it takes years of experience, but a printer makes it easy. A restaurant in Spain uses a Foodini to “re-create forms and pieces” of food that are “exactly the same,” freeing cooks to complete other tasks. In another restaurant, all of the dishes and desserts it serves are 3D-printed, rather than farm to table.

    Nutrition

    Future 3D food printers could make processed food healthier. Hod Lipson, a professor at Columbia University, said, “Food printing could allow consumers to print food to meet their own nutritional needs, like vitamins. So instead of eating a piece of yesterday's bread from the supermarket, you'd eat something baked just for you on demand.”

    Challenges

    Despite recent advancements in 3D food printing, the industry has many challenges to overcome. Currently, most ingredients must be changed to a paste (糊状物) before a printer can use them, and the printing process is quite time-consuming, because ingredients interact with each other in very complex ways. On top of that, most of the 3D food printers now are restricted to dry ingredients, because meat and milk products may easily go bad. Some experts are skeptical about 3D food printers, believing they are better suited for fast food restaurants than homes and high-end restaurants.

    When Johnny, a homeless man, spent his last $20, he wasn't looking at it as an investment — but it's about to pay him huge profits. After he helped a woman who ran out of gas, she returned the favor by raising a lot more on the Internet.

    Kate McClure, 27, was driving to visit a friend when she ran out of gas halfway. “He saw me pull over and knew something was wrong," she wrote. "He told me to get back in the car and lock the doors. A few minutes later, he came back with a red gas can, using his last 20 dollars to make sure I could get home safe."

    She couldn't repay him at that time because she had no cash with her. "I have been stopping by his spot for the past few weeks. I repaid him for the gas and gave him some clothes."

    Kate decided to do more for him, so she started a crowdfunding(众筹) campaign on GoFundMe.com, and it quickly gained far beyond its initial $10,000 goal. When it reached $100,000, the fundraising page was shut down for a time at Johnny's request. Because he didn't want to seem like he was taking advantage of the situation. Finally, Kate said that she restarted it because the public interest had not decreased. She also added that Johnny planned to donate the rest to a good cause.

    According to the New York Post, Johnny wants to get a job at an Amazon warehouse and a department manager from the tech company has already reached out, saying he wants to help Jonny.