A famous teacher was speaking to the students at our school. He began his lesson by holding up a ￡100 bill. Then he said to the three hundred students, "Who would like to have this ￡100 bill?" The students began to put up their hands at once.

    Then he said, "I am going to give this bill to one of you, but first, let me do this." He then made this bill into a ball. Then he said, "Who wants it?" Hands went into the air.

    "Well," he said, "What if I do this?" and he dropped it on the floor and stepped on it. He picked up the dirty, crumpled bill and said, "Who still wants it?" Hands went back into the air.

    "My friends," he said, "You've learned a valuable lesson today. No matter what I did to the money, you still wanted it because it didn't go down in value. It was still worth ￡100.”

     “Many times in our lives, we're dropped, crumpled, and stepped on by the chances we take and the things that happen to us. We feel as if we are worth nothing. But remember, no matter what has happened to you, you will never lose your value: you are always valuable to those who love you. Your value doesn't come from what you drop or whom you know, but WHO YOU ARE.”

    You are special and valuable. Don't ever forget it!

    A black hole is created when a large star burns out. Like our sun, stars are unbelievably hot furnaces(熔炉) that burn their own matter as fuel. When most of the fuel is used up, the star begins to die.

    The death of a star is not a quiet event. First there is a huge explosion. As its outer layer is blasted off into space, the dying star shines as brightly as a billion suns.

    After the explosion, gravity pulls in what's left of the star. As the outside of the star sinks toward the center, the star gets smaller and smaller. The material the star is made of becomes tightly packed together. A star is so solid that a teaspoon of matter from it weighs billions of pounds.

    The more the star shrinks(收缩), the stronger the gravity inside it becomes. Soon the star is very tiny, and the gravity pulling it in is unbelievably strong. In fact, the gravity is so strong that it even pulls light into the star! Since all the light is pulled in, none can go out. The star becomes black when there is no light. Then a black hole is born!

    That's what we know about black holes. What we don't know is this: What happens inside a black hole after the star has been squeezed into a tiny ball? Does it keep getting smaller and smaller forever? Such a possibility is hard to imagine.

    But if the black hole doesn't keep shrinking, what happens to it? Some scientists think black holes are like doorways to another world. They say that as the star disappears from our universe, it goes into another universe. In other words a black hole in our universe could turn into a "white hole" in a different universe. As the black hole swallows(吞噬) light, the white hole shines brightly--somewhere else. But where? A different place, perhaps, or a different time--many years in the past or future.

    Could you travel through a black hole? Right now, no. Nothing we know of could go into a black hole without being crushed(挤压). So far the time being, black hole must remain a mystery.

Black holes are a mystery--but that hasn't stopped scientists from dreaming about them. One scientist suggested that in the future we might make use of the power of black holes. They would supply all of Earth's energy needs, with plenty to spare. Another scientist wondered if a black hole could some day be used to swallow earthly waste--a sort of huge waste disposal(处理) in the sky!

    Eleven leatherback turtles (棱皮龟) are swimming across the Pacific Ocean to the Galapagos Islands in a "race". It will be reported online to attract people's attention to the situation of the endangered (濒危的) animals.

    People have put small tracking devices (跟踪装备) on the turtles so that they can monitor their journeys as they head south from their birthplace to their feeding grounds near the Galapagos, about 1,500 km away.

    People can choose a turtle online and track it at http://www.greatturtlerace.com. The turtle that travels furthest in two weeks' swimming will be the winner.

    There is no prize for the winner of the "race". Rather, they just want to help people take notice of the dangers facing the animal that has lived in the oceans for 100 million years.

    Scientists say 95 percent of the turtles in the Pacific Ocean have disappeared in the last 20 years, because of human activities like fishing, stealing their eggs and building near their homes.

    Thousands of leatherback turtles lived at Playa Grande 10 years ago, but the number has dropped below 100 in the last 5 years.

    The leatherback turtle "race" will not be broadcast on TV at the same time because the turtles leave Costa Rica at different times. Instead, a group will provide a day-to-day showing of the first 14 days of their journeys at the same time as if they were racing.

    The activity will collect money to protect Playa Grande.

    Reader: For six years, I've run an office that has two employees: me and my boss. He used to be so appreciative that I didn't mind doing a little extra, but about two months ago, he started being rude and demanding. Now he even yells when I don't have time to bring his favorite wine to his home after work.

    This change started when we met a wealthy new customer, who is a huge jerk (古怪的人) — my boss's new behavior is just like his.

    My boss is a good man; he and his family have treated me like a little sister. Is there a good way to discuss this with him?

    Karla: Sounds like your new customer has set a bad example to your boss. You need to remind your boss that you're in his corner— but you're not his slave. My suggestions are as follows.

Start with a simple question in a calm moment: "Is everything okay?"

State the truth: "Until recently, I've felt like a valued teammate. But our relationship has become tense. Your expectations of me seem to have changed. Although I used to do occasional personal businesses for you as a favor, now it seems expected."

Draw your lines: "If you think my job description needs to change or my performance is not good enough, let's discuss that. Otherwise, I need you to stop yelling at me and to respect my personal time."

Ideally, you'll get an apology and a promise to do better. After that, it's a matter of reinforcement (加强) . If he starts yelling, look at him with a calm expression. After he cools down, restate his request and add, "Is that correct?" For the unreasonable request, such as fetching his favorite wine after work: "I'm afraid I can't take care of that for you." If he keeps acting like a jerk, there are bosses out there who will better respect your time and talent.

    Karla L. Miller is ready to hear your work dramas. Send your questions to wpmagazine@washpost.com.

    If you find yourself checking your phone first thing in the morning, if you find you're text-messaging while driving, checking your phone instead of working on an important assignment—you are addicted.

    Don't worry. The new NoPhone might be just the thing you need. It looks and feels exactly like a smartphone, but it does nothing. It's just a piece of plastic that you can carry around in your hand to fool yourself.

    NoPhone is currently a prototype(手机模型) that will cost only $12 once it hits the market. Its makers are trying to raise $30,000 in order to cover the production and marketing costs.

    Dutch designer Ingmar Larsen, who helped create the NoPhone, said that he had the idea as a joke along with his friends Van Gould and Ben Langveld. To their great surprise, the idea received a lot of attention online and people from all over the world started placing requests for NoPhone of their own, so that's when the three friends decided to raise money for mass production.

    David H said," I used to sleep with my phone in my hand, but my night terrors would cause me to throw it across the room in an unconscious panic. With the NoPhone, I can still enjoy the comfort of holding a phone in my sleep, without waking up to a broken screen, thanks, NoPhone."

    If you're interested in NoPhone, but concerned about not being able to take selfies anymore, don't worry. The makers do have an update at no extra charge—the mirror sticker. That way, they say, you can enjoy "real-time" selfies with your friends when they're standing right behind you.

    Father's Day is celebrated today in 75 countries around the world. In my personal world, it's a day I like to think of my father's father.

    I learned a lot in my later life from my dad. But I learned something else, as a kid not even yet in school, from my grandfather. I learned to be curious. Little things fathers and grandfathers do can change the life of a child forever. In my case, this change came from necessity: My mom needed someone to look after little Allen, barely 4 years old, during the school day. My grandmother volunteered, and my grandfather came up with a way I could be watched while he worked in his clockmaker's shop.

    He seated me on a chair every day while I was there, right in front of his big workbench. He told me stories. He had a great sense of humor and a funny way of making a "buh-buh-buh" sound when he sensed my attention was weakening, and he encouraged me to ask questions about anything he was doing.

    Naturally, I was usually asking questions about clocks--what made the hands move, what the pendulum(钟摆) did, why you had to stop winding just before the weight hit the stop. Sometimes I just asked about which shiny parts went where.

    Most of all, he showed me how clocks worked. He treated me as if I were a sort of small grown-up. He never talked down to me, never told me I was "too young to understand".

    And so my grandfather granted me two things: A love of clocks, and an everlasting curiosity.

    As a journalist, I turned that fascination into explanations of why computers and software do what they do——and, perhaps even more importantly, why they fail at that task. I haven't been afraid of opening up the innards and looking for what is wrong with the computer.