However wealthy we may be, we can never find enough hours in the day to do everything we want. Economics deals with this problem through the concept of opportunity cost, which simply refers to whether someone's time or money could be better spent on something else.

    Every hour of our time has a value. For every hour we work at one job we could quite easily be doing another, or be sleeping or watching a film. Each of these options has a different opportunity cost—namely, what they cost us in missed opportunities.

    Say you intend to watch a football match but the tickets are expensive and it will take you a couple of hours to get to and from the stadium. Why not, you might reason, watch the game from home and use the leftover money and time to have dinner with friends? This—the alternative use of your cash and time—is the opportunity cost.

    For economists, every decision is made by knowledge of what one must forgo—in terms of money and enjoyment—in order to take it up. By knowing precisely what you are receiving and what you are missing out on, you ought to be able to make better-informed, more reasonable decisions. Consider that most famous economic rule of all: there's no such thing as a free lunch. Even if someone offers to take you out to lunch for free, the time you will spend in the restaurant still costs you something in terms of forgone opportunities.

    Some people find the idea of opportunity cost extremely discouraging: imagine spending your entire life calculating whether your time would be better spent elsewhere doing something more profitable or enjoyable. Yet, in a sense it's human nature to do precisely that—we assess the advantages and disadvantages of decisions all the time.

    In the business world, a popular phrase is “value for money.” People want their cash to go as far as possible. However, another is fast obtaining an advantage: “value for time.” The biggest restriction on our resources is the number of hours we can devote to something, so we look to maximize the return we get on our investment of time. By reading this passage you are giving over a bit of your time which could be spent doing other activities, such as sleeping and eating. In return, however, this passage will help you to think like an economist, closely considering the opportunity cost of each of your decisions.

    This is the incredible school where the headteacher's unique dedication to handwriting practice means EVERY pupil is ambidextrous.

Only ten percent of the population are left-handed, and only ONE percent can write with both hands. But all 300 students at Veena Vandini School in India can write with both their left and right hand, with some able to do both at the same time—in different languages.

    Every 45-minute lesson features 15 minutes devoted to handwriting practice, to make sure all students at the remote rural school have the skill.

    The school, which was founded in 1999, is located in a remote area, in Singrauli district, Madhya Pradesh. School founder and former solider Vp Sharma said he was inspired to demand the lessons by India's first president.

     “I read in a magazine that Dr Rajendra Prasad used to write with both hands. This inspired me to give it a try. Later, when I launched my school at my native village, I tried training the students.

     “We began training students from standard I and by the time they reach standard III, they were comfortable writing with both the hands. Students of standard VII and VIII can write with speed and accuracy. Further, they can write two scripts simultaneously, one with each hand.

     “Students also know several languages, including Urdu.”

    Mr Sharma said their unique dedication to handwriting led South Korean researchers to visit and study the pupils two years ago, to find out more about ambidexterity.

    You may not have heard of it before, but solid rain (固体雨)has been helping Mexican farmers fight droughts(干旱) for over ten years. The magic solid rain looks like sugar and it can take in water up to 500 times as its own size and keep it in the ground for up to a year.

    The story of solid rain began in 1970, when American scientists developed a product used to take in water and help keep babies' bottoms dry. However, a Mexican chemical engineer saw this magic product as an opportunity to fight the drought. He developed a different kind of the product, which could be mixed with soil and slowly feed water to crops over a long period of time. His company, Solid Rain, has been quietly selling the product to Mexican farmers for over 10 years.

    Solid rain seems to be working wonders in Mexico. However, it has not come into use around the world. Well, that's mainly because a lot of people still don't know about it. The Mexican company has invested (投资) almost nothing into marketing, relying instead on word of mouth between Mexican farmers. However, recently, they have gotten requests from other dry countries like India and Australia.

    Solid rain has received the Ecology and Environment Award, but it has also received some negative views. Dr. Linda Scott says that the product is hardly new and that there is no scientific evidence that it can hold water for a year or last in the ground for ten years. Besides, solid rain can cause more harm than good in certain conditions.

    However, real-life use seems to show that solid rain is actually of great use to their farms. Frank Torres, a former green bean farmer used to rely on it even though drought wasn't such a big issue. He said that the production had increased by 50%.

Teen Volunteers

    The zoo supports future conservation by having the youth involved in voluntary jobs. We have popular summer year-round programs that are designed to be fun and educational while building job readiness skills and inspiring youth to appreciate, care for, and conserve nature.

    ◆Zoo Crew

    Volunteer on a team to restore wildlife habitat at Lake Merced and Mountain Lake in San Francisco.

    Ages11-14

    Program runs: September through June

    Hours: One Saturday per month, form 10 a. m. to 12 p. m.

    The Zoo Crew will hold a necessary training for all prospective volunteers in August at the Zoo.

    ◆Nature Trail

    Nature Trailers work in close proximity (接近) to the Zoo's ambassador animal collection, and teach guests about adaptations and conservation. Nature Trailers will learn to handle a few small mammals and reptiles.

    Ages 12-14 (must be 12 by Memorial Day)

    Program runs: Memorial Day to Labor Day

    Hours: 2 days per week, 10 a. m. to 4: 45 p. m.

    ◆Talk on the Wild Side

    Learn to handle amazing animals like livestock and arthropods (节肢动物) while giving informational talks to zoo visitors. Use biofact carts to educate the public.

    Ages 14-17

    Program runs: Memorial Day to Labor Day

    Hours: 2 days per week, 9: 30 a. m. to 4: 30 p. m.

    ◆Zoo Teacher Assistant

    Help kids explore the world of animals through zoo tours, crafts, games and assist Zoo Camp teachers with activities. Gain practical work experience with children.

    Ages14-17

    Program runs: mid-June through mid-August

    Hours: A daily half-day or full-day shift for a minimum of four weeks over the course of the summer.

    BELJLNG—Eating at a Beijing restaurant is usually an adventure for foreigners, and particularly when they get the chance to order "chicken without sex life" or "red burned lion head".

    Sometimes excited but mostly confused, embarrassed or even terrified, many foreigners have long complained about mistranslations of Chinese dishes. And their complaints are often valid, but such an experience at Beijing's restaurants will apparently soon be history.

    Foreign visitors will no longer, hopefully, be confused by oddly worded restaurant menus in the capital if the government's plan to correctly translate 3, 000 Chinese dishes is a success and the translations are generally adopted.

    The municipal (市政) office of foreign affairs has published a book to recommend English translations of Chinese dishes, which aims to help restaurants avoid bizarre translations. "It provides the names of main dishes of famous Chinese cuisines in plain English," an official with the city's Foreign Affairs office said, "Restaurants are encouraged to use the proposed translations, but it will not be compulsory." It's the city's latest effort to bridge the culture gap for foreign travelers in China.

    "The book is a blessing to tourist guides like me. Having it, I don't have to rack my brains trying to explain Chinese dishes to foreign travelers," said Zheng Xiaodong, a 31-year-old employee with a Beijing-based travel agency.

    "I will buy the book as I major in English literature and I'd like to introduce Chinese cuisine culture to more foreign friends," said Han Yang, a postgraduate student at the University of International Business and Economics.

    It is not clear if the book will be introduced to other parts of China. But on Tuesday, this was the most discussed topic on weibo.com, China's most popular micro-blogging site.

A farmer grew some vegetables in his garden. One day his wife was ill and he had no money. He had to sell some cabbages and carrots in the market. The next morning he took two baskets of vegetables to town. But it was raining hard that afternoon and there were few people in the street. When his vegetables were sold out, it was dark. He bought some medicine and hurried to his village. 

On his way home he saw a person lying on the snow. He placed his baskets on the ground and was going to help the person to get up. At that time he found it was a dead man and there was much blood on his body. He was so afraid that he ran away quickly, without taking the baskets with him. 

The next afternoon the farmer was sent to the police station. Having shown the baskets, an officer asked: "Are these yours?" "Yes, sir." the farmer answered timidly (胆怯)."Have you killed the man?" "No, no, sir." the farmer said in a hurry. "When did you see the dead man?" "About seven last evening." "Did you see who killed the man?" "No, Sir." The officer brought out a knife and asked, "Have you seen it yet?" "No, Sir." The officer became angry and told the policemen to beat him up and send him into prison. 

That evening the officer went on trying. Pointing to the knife, he asked again, "Have you seen it yet?" "Yes, Sir." The officer was happy and asked, "When and where?" "I saw it here this afternoon, sir."