After a year of examining many studies concerning whether homework is effective, NYC P. S. Elementary School decided that math worksheets and essay assignments were actually a waste of time. In February, Principal Jane Hsu sent a letter to parents stating that the Pre-K(学前班) through fifth grade students wouldn't be given any traditional homework to encourage kids to free time for reading, playing outside, or doing activities they enjoy.

    “The negative effects of homework have been well established.” Hsu wrote in a note to parents. “They include, children's frustration and exhaustion, lack of time for other activities and family time and, sadly for many, loss of interest in learning.”

    Some parents, however, disagree with the policy change, believing that a lack of focus will cause children to fall behind. Homework has been part of education from the beginning, and has increased in amount in recent years.

    Hsu's advice that children should read and spend time with their families has upset some parents to the point of considering pulling their children out of the school. This group feels that homework gives children a goal to work toward. Others feel so strongly about the importance of homework that they have begun giving their own homework to their children.

    An Australian Childhood Foundation survey finds that 71% of Australian parents feel they don't spend enough quality time with their children mainly because of the time spent running the household or the time spent helping with homework. Education experts in Australia are saying that parents should stop helping. Doing so will give kids more independence, give parents more free time, and help reduce the number of arguments caused by homework in the family.

    While some research suggests that homework has little academic benefit for elementary students, other researches show homework can help kids develop independence, and confidence. It can also contribute to a sense of belonging or control over their lives. When parents try to help their children with homework, the assistance can take away that feeling and can also make working parents more tired.

    Most people know precious gemstones (宝石) by their appearances. An emerald flashes deep green, a ruby seems to hold a red fire inside, and a diamond shines like a star. It's more difficult to tell where the gem was mined, since a diamond from Australia or Arkansas may appear the same to one from the Democratic Republic of the Congo. However, recently, a team of scientists has found a way to identify a gemstone's origin.

    Beneath the surface of a gemstone, on the tiny level of atoms and molecules（分子）, lie clues (线索) to its origin. At this year's meeting of the Geological Society of America in Minneapolis, Catherine McManus reported on a technique that uses lasers (激光) to clarify these clues and identify a stone's homeland. McManus directs scientific research at Materialytics, in Killeen, Texas. The company is developing the technique. “With enough data, we could identify which country, which mining place, even the individual mine a gemstone comes from,” McManus told Science News.

    Some gemstones, including many diamonds, come from war-torn countries. Sales of those “blood minerals” may encourage violent civil wars where innocent people are injured or killed. In an effort to reduce the trade in blood minerals, the U.S. government passed law in July 2010 that requires companies that sell gemstones to determine the origins of their stones.

    To figure out where gemstones come from, McManus and her team focus a powerful laser on a small sample of the gemstone. The technique is called laser-induced breakdown spectroscopy. Just as heat can turn ice into water or water into steam, energy from the laser changes the state of matter of the stone. The laser changes a miniscule part of the gemstone into plasma, a gas state of matter in which tiny particles（微粒）called electrons separate from atoms.

    The plasma, which is superhot, produces a light pattern. (The science of analyzing this kind of light pattern is called spectroscopy.) Different elements produce different patterns, but McManus and her team say that gemstones from the same area produce similar patterns. Materialytics has already collected patterns from thousands of gemstones, including more than 200 from diamonds. They can compare the light pattern from an unknown gemstone to patterns they do know and look for a match. The light pattern acts like a signature, telling the researchers the origin of the gemstone.

    In a small test, the laser technique correctly identified the origins of 95 out of every 100 diamonds. For gemstones like emeralds and rubies, the technique proved successful for 98 out of every 100 stones. The scientists need to collect and analyze more samples, including those from war-torn countries, before the tool is ready for commercial use.

    Scientists like Barbara Dutrow, a mineralogist from Louisiana State University in Baton Rouge, find the technique exciting. “This is a basic new tool that could provide a better fingerprint of a material from a particular locality,” she told Science News.

    Most kids go to school during the day and come home to their families or caregivers at night．Sometimes kids can't go home every night so they board or live at school during term-time．

    Whatever the reason for going to boarding school, living with a group of people is very different from living with your family．You have to learn to get on with others, be responsible for looking after your own stuff and follow the rules that are there to make everyone's life pleasant and safe.

The following are some tips from boarders.

    "Remember that the other new students are probably as shy as you are．If you don't talk first and try to make friends, it may not happen．"

    "Don't hold things back inside you．The more you talk, the easier it gets．You can talk to older boarders as well as adults．They understand what you are feeling—they've been through it too．"

    "Be respectful of others' space and give them privacy．Having people around all the time means you don't get much time to yourself."

    "Join in sports and other afterschool activities．You'll meet lots of new people who are interested in the same things as you．And keeping busy will help you get over feeling homesick．"

    "If you are a weekly boarder or go home most weekends it can be harder to make friends, so see if you can organize to stay in for a weekend."

    "Make friends with non-boarders too．It's good to visit someone's home sometimes."

    "Boarding has its ups and downs, you get homesick and sometimes the food is not that great but most of the time it is like being in one big family．You make friends that you know you'll keep for the rest of your life．"

    Would it surprise you to learn that, like animals, trees communicate with each other and pass on their wealth to the next generation?

    UBC Professor Simard explains how trees are much more complex than most of us ever imagined. Although Charles Darwin thought that trees are competing for survival of the fittest, Simard shows just how wrong he was. In fact, the opposite is true: trees survive through their cooperation and support, passing around necessary nutrition “depending on who needs it”.

    Nitrogen (氮) and carbon are shared through miles of underground fungi (真菌) networks, making sure that all trees in the forest ecological system give and receive just the right amount to keep them all healthy. This hidden system works in a very similar way to the networks of neurons (神经元) in our brains, and when one tree is destroyed, it affects all. Simard talks about “mother trees”, usually the largest and oldest plants on which all other trees depend. She explains how dying trees pass on the wealth to the next generation, transporting important minerals to young trees so they may continue to grow. When humans cut down “mother trees” with no awareness of these highly complex “tree societies” or the networks on which they feed, we are reducing the chances of survival for the entire forest “We didn't take any notice of it.” Simard says sadly. “Dying trees move nutrition into the young trees before dying, but we never give them chance.” If we could put across the message to the forestry industry, we could make a huge difference towards our environmental protection efforts for the future.

    Childhood is a happy time, right? Not necessarily. Consider these facts.

Depression(抑郁症) may occur in as many as 1 in 33 children.

    Once a child has an episode of depression, he or she has a 50 percent chance of experiencing another episode in the next 5 years.

    Suicide(自杀) is the 6th leading cause of death for 5-to-15-year-olds.

    If your child experiences 5 or more of these signs or symptoms for at least 2 weeks, he or she may be experiencing depression or mental illness.

    Sometimes, a child who causes problems at school or at home may actually be depressed, according to the American Academy of Child and Adolescent Psychiatry.

    If you think your child may be depressed, it's important to have your child treated. Discuss your child's problems with his or her doctor. The doctor may suggest a referral to a children's psychologist or psychiatrist.

D

    Children as young as ten are becoming dependent on social media for their sense of self-worth, a major study warned.

    It found many youngsters(少年）now measure their status by how much public approval they get online, often through "like". Some change their behavior in real life to improve their image on the web.

    The report into youngsters aged from 8 to 12 was carried out by Children's Commissioner (专员）Anne Longfield. She said social media firms were exposing children to major emotional risks, with some youngsters starting secondary school ill-equipped to cope with the tremendous pressure they faced online.

    Some social apps were popular among the children even though they supposedly require users to be at least 13.The youngsters admitted planning trips around potential photo-opportunities and then messaging friends—and friends of friends — to demand "likes" for their online posts.

    The report found that youngsters felt their friendships could be at risk if they did not respond to social media posts quickly, and around the clock.

    Children aged 8 to 10 were "starting to feel happy" when others liked their posts. However, those in the 10 to 12 age group were "concerned with how many people like their posts", suggesting a "need" for social recognition that gets stronger the older they become.

    Miss Longfield warned that a generation of children risked growing up "worried about their appearance and image as a result of the unrealistic lifestyles they follow on platforms, and increasingly anxious about switching off due to the constant demands of social media.

    She said: "Children are using social media with family and friends and to play games when they are in primary school. But what starts as fun usage of apps turns into tremendous pressure in real social media interaction at secondary school."

    As their world expanded, she said, children compared themselves to others online in a way that was "hugely damaging in terms of their self-identity, in terms of their confidence, but also in terms of their ability to develop themselves".

    Miss Longfield added: "Then there is this push to connect—if you go offline, will you miss something, will you miss out, will you show that you don't care about those people you are following, all of those come together in a huge way at once."

    "For children it is very, very difficult to cope with emotionally." The Children's Commissioner for England's study—life in Likes—found that children as young as 8 were using social media platforms largely for play.

    However, the research—involving eight groups of 32 children aged 8 to 12—suggested that as they headed toward their teens, they became increasingly anxious online.

    By the time they started secondary school—at age 11—children were already far more aware of their image online and felt under huge pressure to ensure their posts were popular, the report found.

    However, they still did not know how to cope with mean-spirited jokes, or the sense of incompetence they might feel if they compared themselves to celebrities(名人）or more brilliant friends online. The report said they also faced pressure to respond to messages at all hours of the day—especially at secondary school when more youngsters have mobile phones.

    The Children's Commissioner said schools and parents must now do more to prepare children for the emotional minefield(雷区）they faced online. And she said social media companies must also "take more responsibility". They should either monitor their websites better so that children do not sign up too early, or they should adjust their websites to the needs of younger users.

    Javed Khan, of children's charity Bamardo's, said: "It's vital that new compulsory age-appropriate relationship and sex education lessons in England should help equip children to deal with the growing demands of social media.

    "It's also hugely important for parents to know which apps their children are using."