Time zones: what time is it in London, England, when U.S. kids on the East Coast are getting up for school? To figure that out, it helps to understand time zones.
Suppose you live in Miami, Florida “Miami” redirects here. For the Native American tribe, see Miami tribe.
Miami is a major city in southeastern Florida, in the United States. It is the county seat of Miami-Dade County. Miami is a gamma world city with an estimated population of 404,048. , and get up at 7 a.m. for school. What time is it in London?
Our map gives you the answer--if you know how to use it. The map shows the world's 24 time zones, which begin at the prime meridian prime meridian, meridian that is designated zero degree (0°) longitude, from which all other longitudes are measured. By international convention, it passes through the original site of the Royal Observatory in Greenwich, England; for this reason, it is sometimes , 0[degrees] longitude. (See the dotted line on the map.)
The prime meridian passes through Greenwich (a part of London). So its time zone became known as Greenwich Mean Time Greenwich mean time or Greenwich meridian time (GMT), the former name for mean solar time at the original site of the Royal Observatory in Greenwich, England, which is located on the prime meridian. . Today's time system is called Coordinated Universal Time See UTC.
(time, standard) Coordinated Universal Time - (UTC, World Time) The standard time common to every place in the world. UTC is derived from International Atomic Time (TAI) by the addition of a whole number of "leap seconds" to synchronise it with Universal Time 1 (UTC (Coordinated Universal Time, Temps Universel Coordonné) The international time standard (formerly Greenwich Mean Time, or GMT). Zero hours UTC is midnight in Greenwich, England, which is located at 0 degrees longitude. ).
When you travel east from the prime meridian, you need to set your watch forward by one hour for each time zone you enter. When traveling west, you must set your watch back one hour for each time zone.
Reading a time-zone map isn't as hard as it may seem. Look at the color bars at the top and bottom of the map. Each top bar shows the time in that zone when it is 12 noon in London. Each bottom bar tells you how many hours to add or subtract from UTC to calculate the time for that zone. So when it is 7 a.m. in Miami, it is 12 noon in London.
Bends in the Rule
The day of the week changes when you cross the international date line, located at 180[degrees] longitude in the Pacific Ocean. The date just west of the line is one day later than the date just east of the line.
Time zones can be irregular. Some countries, like Iran, observe a time zone that is half an hour different from the standard time zone.
And look at China. It stretches across four time zones, but its government insists that all clocks in China read the same time as in the capital, Beijing!
1. When the Seattle Seahawks
New York, Middle Atlantic state of the United States. It is bordered by Vermont, Massachusetts, Connecticut, and the Atlantic Ocean (E), New Jersey and Pennsylvania (S), Lakes Erie and Ontario and the Canadian province of ? --
2. If the President speaks at 9 p.m. from the White House, what time is it in Los Angeles Los Angeles (lôs ăn`jələs, lŏs, ăn`jəlēz'), city (1990 pop. 3,485,398), seat of Los Angeles co., S Calif.; inc. 1850. ? --
3. When a baseball game begins at 7 p.m. in Chicago, Illinois, what time is it in Anchorage, Alaska? --
4. What South American city on the map is in the same time zone as New York City New York City: see New York, city.
New York City
City (pop., 2000: 8,008,278), southeastern New York, at the mouth of the Hudson River. The largest city in the U.S. ? --
5. If you fly from New York to Paris, how should you set your watch when you land? --
6. A U.S. soldier calls from Baghdad, Iraq, at 11 p.m., Iraq time. What time is it at his home in Miami, Florida? --
7. Each new calendar day begins at the International Date Line, which is based on which line of longitude? --
8. Suppose you fly east from Tokyo, Japan. If you reach the International Date Line at noon on Wednesday, what day is it after you cross the line? --
9. If it is 2 a.m. in Honolulu, Hawaii, what time is it on the International Date Line? --
10. How many time zones does the U.S. have, including Alaska, Hawaii, and U.S. territories? --
2. 4 p.m.
3. 6 p.m.
4. 4 p.m.
5. Quito [Ecuador]
6. When you land, set your watch six hours ahead [later in the day].
7. 3 p.m.
9. noon on Tuesday
10. 1 a.m.
Time Zones p. 20
* Reinforcing map-reading skills.
* Applying basic math skills in a real-world context.
 Words to Know
* Greenwich mean time [GMT (Greenwich Mean Time) See UTC.
GMT - Universal Time 1 ] and coordinated universal time [UTC]: GMT was adopted in 1884. New technology made timekeeping truer to Earth's rotation (the basis for 24-hour days), so UTC was adopted in 1964. For accuracy, it adds a leap second to the year when necessary, making the last minute of June or December 61 seconds long instead of the usual 60.
 Before Reading
Through most of history, human beings got by without time standards. That changed with the spread of railroads. The railroad made it possible to travel long distances so quickly that differences in schedules caused confusion. In 1884, delegates from 25 countries met to devise an international standard.
Reading prompt: Why do we adjust our watches when we travel?
 After Reading
* For more: On the 1884 International Meridian Conference The International Meridian Conference was a conference held in October 1884 in Washington, D.C. in the United States to determine the Prime Meridian of the world. It was held at the request of U.S. President Chester A. Arthur. Twenty-five nations were represented by 41 delegates. : greenwichmean time.com/info/conference.htm.
 Keep It Going
Have students plan a round-the-world trip. Then have them figure out at what time, in each place they visit, they would have to make a call in order to reach their parents at home every night at 10:30?
* How Time Works. Includes section on time zones. people.howstuffworks.com/time.htm
* World Time Zones. Time zone maps with current times. worldtimezone.com
* Time, Navin Sullivan (Benchmark Books, 2006). Timepieces, time zones, leap years, radiocarbon dating, and other wags we measure time. Grades 4-7.
* A Wrinkle in Time, Madeleine L'Engle (Holtzbrinck Publishers, 2007). Classic children's novel. Also available as audio disk and as a movie version (2004) in DVD DVD: see digital versatile disc.
in full digital video disc or digital versatile disc
Type of optical disc. The DVD represents the second generation of compact-disc (CD) technology. or VHS (Video Home System) A half-inch, analog videocassette recorder (VCR) format introduced by JVC in 1976 to compete with Sony's Betamax, introduced a year earlier. .