Bill Gates recently predicted that online learning will make place-based colleges less significant, and five years from now, students will be able to find the best lectures in the world online. I applaud Mr. Gates. But what's taking us so long?

    As early as 1997, MIT(麻省理工) decided to post videos of all university lectures online. for free, for all people. But today, how many students have you met who mastered advanced mathematics or nuclear physics from an MIT online video? Unfortunately, the answer is not many. The problem is the poor quality of online education websites and the experience they provide to students. Those who go to the MIT website and watch courses online are surely very smart people, but it's not like playing a video game such as World of Warcraft. Only the most ardent students, those who are highly motivated, will devote themselves to studying these boring online videos.

    The real question is why we aren't spending more to develop better online education platforms. Where is the Avatar of education? Think about this. The market for Hollywood films per year is worth around 30 billion USD. Education in the world is a trillion-dollar-a-year market, hundreds of times bigger than Hollywood movies. Yet the most expensive digital learning system ever built cost well under 100 million dollars.

    Bill Gates' prediction is going to happen. There is no doubt about it. But it will only happen when we create high level educational content and experiences that engage and excite more than has ever been possible in the real world.

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    “Indeed,” George Washington wrote in his diary in 1785, “some kind of fly, or bug, had begun to eat the leaves before I left home.” But the father of America was not the father of bug. When Washington wrote that, Englishmen had been referring to insects as bugs for more than a century, and Americans had already created lightning-bug(萤火虫). But the English were soon to stop using the bugs in their language, leaving it to the Americans to call a bug a bug in the nineteenth and twentieth centuries.

    The American bug could also be a person, referring to someone who was crazy about a particular activity. Although fan became the usual term, sports fans used to be called racing bugs, baseball bugs, and the like.

    Or the bug could be a small machine or object, for example, a bug-shaped car. The bug could also be a burglar alarm, from which comes the expression to bug, that is, “to install (安装) an alarm”. Now it means a small piece of equipment that people use for listening secretly to others' conversation. Since the 1840s, to bug has long meant “to cheat”, and since the 1940s it has been annoying.

    We also know the bug as aflawin a computer program or other design. That meaning dates back to the time of Thomas Edison. In 1878 he explained bugs as “little problems and difficulties” that required months of study and labor to overcome in developing a successful product. In 1889 it was recorded that Edison “had been up the two previous nights discovering ‘a bug' in his invented record player.”

    Gravity signals that race through the ground at the speed of light could help seismologists(地震学家) get a better handle on the size of large, destructive quakes soon after they hit，a study suggests. The tiny changes in Earth's gravitational field, created when the ground shifts, arrive at earthquake monitoring stations well before earthquake waves.

    “The good thing we can do with these signals is have quick information on the magnitude (震级) of the quake,” says Martin Vaillée, a seismologist at the Paris Institute of Earth Physics.

    Earthquake equipment in China and South Korea picked up gravity signals immediately after the magnitude-9. 1 Tohoku earthquake that destroyed parts of Japan in 2011. The signals appear as tiny accelerations on earthquake-recording equipment, more than a minute before the seismic waves show up.

    “We can look before the earthquake waves arrive,” says Vallée. “If we see nothing, we can say that the quake that made these was maybe large, but not huge. If we see the signals, it means we really have a very big quake. ”

    Had seismologists been monitoring for gravity changes, they might have realized sooner just how big the Tohoku earthquake was. A small increase in an earthquake's magnitude means a large change in the energy released by the quake-and the destruction expected. That information is important for emergency responders as they decide what resources to arrange.

    It'll be a major contribution if gravitational waves can beat down the time needed to know that a big earthquake is big. But much work remains before gravity signals can be considered a reliable tool in the vital minutes after a big quake. A few extra minutes of warning can save lives, particularly in coastal areas where people can flee ahead of an incoming tsunami.

    A recent study surveyed 5,000 British families about their experiences with volunteering and their mental health. Participants completed the same survey every two years from 1996 to 2008.

    About 20 percent of the survey participants reported doing regular unpaid work Researchers found that these volunteers also scored highest on their mental health scores. The two were linked so directly that the more a person volunteered, the happier they were.

    One could argue a chicken-and-egg theory: happier people are more likely to have the time, money, energy and resources to give back to others. But even when researchers adjusted for education, social class and total health, the link was there, suggesting that the mental increase came from volunteering and not the other way around.

    According to Dr. Stephen G. Post, author of The Hidden Gifts of Helping, when you help others, your brain releases feel-good chemicals, which can help cells repair themselves and grow. And this translates to better health.

    So volunteering can help improve both your physical and mental health—on one condition. You have to mean it. People who volunteered for "self-oriental" reasons, either because they were forced to do so for work or school or because they were trying to get away from problems in their lives, had a mortality（死亡率）risk that was similar to those who didn't volunteer at all. It was only when people were volunteering out of a true sense of sympathy that they saw any health benefits.

    So whether it's arranging books at the library or walking dogs at the animal shelter, find a cause that's important to you and give it a try. Volunteering is a good way to develop a sense of connection that not only helps your community, but may also be good for you.

    How does a sunset work? We love to look at one, but Jolanda Blackwell wanted her eighth-graders to really think about it and question.

    So Blackwell had her students watch a video of a sunset as part of a physics lesson on motion. "I asked them: ' So what's moving And why' " Blackwell says. Some thought the sun was moving; others knew that a sunset is the result of the Earth spinning around on its axis. "Usually, my biggest challenge is trying to keep them patient," she says. "They just have so many burning questions."

    "Every day, we meet new information," says Charan Ranganath, a psychologist. Ranganath was curious to know why we keep some information and forget other things. So he got 19 volunteers and asked them to review more than 100 questions. When the participants' curiosity was aroused, the parts of' their brains that regulate pleasure and reward lit up. Curious minds also showed increased activity in the brain, which is involved in greater memories.

    "Curious brains are better at learning not only about the subject at hand but also dull information. This is a phenomenon teachers can use in the classroom," says Evie Malaia, a professor. "Say a kid wants to be an astronaut," she says. NL Well, how do you link that goal with learning multiplication tables(乘法表)" "A teacher may choose to ask her class an interesting word problem that involves space exploration," Malaia says. Students may remember the answer to the word problem, but they'll also remember how they found the answer through multiplication.

    What Ranganath wants to know most is why some people seem naturally more curious than others. Lots of factors, including stress, aging and certain drugs  affect dopamine(多巴胺) processing in the brain. "If we could figure these things out, we could help those who may just seem bored," Ranganath says.

    Blackwell says she doesn't have to deal with that problem too often. She says her students love exploring the mysterious unknowns in science: What happens when a car crashes. How do rainbows work "I tell my kids there's no dumb questions," Blackwell says. "That's science: asking questions and seeking answers."

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