6 . It was a February afternoon in a Brooklyn classroom. Sixteen-year-old Taylor Engler came face to face with a cow. But it was all in her head. She was transported by a virtual reality (VR) headphone. It took the Berkeley Carroll School junior and eight other classmates to a northern New York farm. The farm was 250 miles away. For students, the technology means field trips are no longer kept within the length of a bus ride.

It's unknown how many classrooms have or will use the technology, but experts say few classrooms do or will do. Headphones that require a user's phone can cost as little as $20 or $30, but systems and software for classes run into thousands of dollars. The problem of not having good software is disappearing as more companies enter the market. But the rules for use haven't kept abreast of the development of the technology. In New York, for example, virtual reality lab experiments are not included in the state's hands-on lab time requirements.

Experts say science classes are where virtual reality holds promise for classrooms. “The biggest problem, I think, is going to be how closely it mimics the real world." That's according to David Evans, the director of the National Science Teachers Union. However, he said, “The ability to do dangerous things and to run many, many more cases in a virtual space as opposed to the real physical space stands for a huge learning chance.”

Lamb taught chemistry and he agreed. “Too often in schools, when you do experiments in labs, you mix these together, you mix those together and you get this result. And if you don't get that result, you have done something wrong. But we don't have enough resources for you to redo it, “he said. “In virtual reality, all I do is hit reset on the computer. I don't have to actually use chemicals.”

7 . The concept of planning entire communities before their construction is an ancient one. In fact, one of the earliest such cities on record is Miletus, Greece, which was built in the 4th century BC. Throughout the Middle Ages and the Renaissance various planned communities (both theoretical and actual) were conceived (构思). Leonardo da Vinci designed several cities that were never constructed. Following the Great Fire of London in 1666, the architect Christopher Wren created a new master plan for the city, combining park land and urban space. Several 18th century cities, including Washington D.C., New York City, and St Petersburg, Russia, were built according to comprehensive planning.

One of the most important planned city concepts, the Garden City Movement, arose in the latter part of the 19th century as a reaction to the pollution and crowding of the Industrial Revolution. In 1898, Ebenezer Howard published the book To-Morrow: A Peaceful Path for Real Reform in which he laid out his ideas concerning the creation of new economically sustainable towns. Howard believed that these towns should be limited in size and density, and surrounded with a belt of undeveloped land. The idea gained enough attention and financial backing to lead to the creation of Letchworth, in Hertfordshire, England. This was the first such 'Garden City'. After the First World War, the second town built following Howard's ideas, Welwvn Garden City, was constructed.

In the early 1920s, American architects Clarence Stein and Henry Wright, inspired by Howard's ideas and the success of Letchworth and Welwyn, created the city of Radbum, New Jersey. Conceived as a community which would be safe for children, Radbum was intentionally designed so that the residents would not require automobiles. Several urban planning designs were pioneered at Radbum that would influence later planned communities, including the separation of pedestrians and vehicles, and the use of 'superblocks', each of which shared 23 acres of commonly held parkland.

In America, following the stock market crash of 1929, there was great demand for both affordable housing and employment for workers who had lost their jobs. In direct response to this, in 1935 President Roosevelt created the Resettlement Administration, which brought about a total of three greenbelt towns: Greenbelt, Maryland; Greenhills, Ohio; and Greendale, Wisconsin. These towns contained many of the elements of the Garden City Movement developments, including the use of superblocks and a 'green belt' of undeveloped land surrounding the community.