Modern Ways of Telling Time
Sundials, water clocks, and hourglasses could help tell time. But had many disadvantages for everyday use. Some were very heavy, some were easily broken, and many depended on the sun to work. As humans began to rely more on time telling deices, that began to develop timekeepers that were more accurate and precise, whatever the conditions.
Mechanical clocks, represented a big step forward in telling time. These clocks used physics principles of weights and balances to mark out increments of time over a 12-hour period. The first mechanical clocks had appeared by 1300 CE in Europe. They were large in order to house the weights required and didn’t keep accurate time. By the 1600’s European scientists had discovered that adding a pendulum, a rod-like weight that swings from side to side and contains a clock mechanism, greatly increased a clock’s accuracy and preciseness and allowed it to record minutes and seconds as well as hours. Mechanical clocks are still in use today. These analog clock show a round clock face with a short hour hand and a longer minute hand that moves forward one second at a time.
The first watches, timepieces that people could easily wear or carry, appeared in Italy in the early 1400’s and measured time through a system of coiled springs. The time-keeping mechanism was built inside a metal ball with a lid that could be raised to see the time, and the entire watch was placed in a pocket or hung from a belt. As improvements were made to coiled springs and mechanisms, watches became smaller and more accurate.
Watches and clocks are used today throughout the world. Many modern clocks and watches contain a quartz crystal, a crystalline form of a hard, glassy mineral called silicone dioxide. A digital watcher clock is powered with batteries and a quart crystal instead of coils and springs and usually shows the time as numbers (e.g., 11:10, 6:42).
As people saw how telling time allowed them to work more efficiently or travel more easily, they began to think of ways of standardizing time to meet their common needs. One result was standard time, which divides the Earth from top to bottom into 24 equal time zones. Each time zone reflects period of time in the 24-hours it takes for the earth to pass once through the prime meridian, the longitude meridian set at 0 degrees.
Standard time was once the most common method people used to record time so that it was it was constant and predictable from one place to the next. The time in each zone was approximately 1 hour later than the time zone to its west and 1 hour earlier than the time zone to its east. In 1884, time measured this way was called Greenwich Mean Time (GMT) because the prime meridian passed through Greenwich England.
On January 1, 1972, after adjustments that allowed for slight variations in the rotation of the Earth, Universal Time Coordinate (UTC), a new, highly accurate system, was adopted around the world as the official measure of time for the planet. However, Greenwich, England is still used as the zero point for the world’s time zones.
During the mid-1800’s, Europe and North America were experiencing the Industrial Revolution, a time of great technological change that resulted in the building of ,Amy factories and railroads. This created the need for very precise and universal time-keeping. For example, saying that the train left “at dawn” was not enough for all passengers to arrive exactly on time. At first, each train company made up its own schedule. That worked for short distances in some parts of some countries, but did not work when people or goods needed to travel from one side of a large country or area to another and arrive at certain time. There were too many complicated and confusing schedules.
In many countries, the need for precise and universal ways of calculating time resulted in the adoption of four ways of manipulating time still used today. The first two, standard time and time zones have been mentioned above. By the early 1880’s, railway companies in the U.S., Canada, and Great Britain had divided land Ito time zones, each zone operating under its own time. In 1884, at the International Prime Meridian Conference in Washington DC, these railway companies persuaded countries around the world to agree on global time zones and standard time within each zone, whatever part of the world it encompassed.
These standardized ways of calculating time were adopted first by the railway companies, then by factories, then by cities where factories and railroads operated.
A third effort to standardize time in the early 1880s resulted in the establishment of the International Date Line, an imaginary line drawn through the PacificOcean on or near the 180th meridian (that is, 180 degrees from the prime meridian). It marks where travelers and navigators on a voyage on the Pacific change their date by one full day. The traveller moving west adds an hour for every 15 degrees of longitude traveled because moving in a westerly direction involved constant adjusting to the rotation of the Earth around the sun. The traveler going west thus adds a day when crossing the International Date Line, and going east, subtracts a day.
A fourth way of standardizing was daylight saving, a system of getting clocks 1 hour ahead of standard time so that sunrise and sunset seem to happen at a later hour. Daylight saving tries to take advantage of the maximum number of daylight hours available for school and work, especially farm work that in the spring and summer benefits from longer evenings. Not all countries or regions within countries agree with or follow daylight saving. Countries who do follow daylight saving set their clocks ahead 1 hour in the spring, usually the first Sunday of April ,then set them back 1 hour to standard time on the last Sunday of October. France, the U.S, sand Canada are three countries that follow daylight saving for part of the year to make better use of daylight hours.
Did you know?
Just about place in the world could have become the prime meridian starting point. But in 1904, when standard time was invented, it was the British horologists who decided to make England the starting point.
Did you know?
Some environmentalists and countries see daylight saving asa way of reducing energy conception because it maximizes the use of daylight, therefore minimizing electricity use for heat and lighting. The idea to save energy during daylight was first introduced in 1916, around the time of World War I. Since then, in times of war or high energy prices, some countries have temporarily increased the months of daylight saving. Other countries feel it is too confusing to have everyone turning their clocks ahead or behind twice a year.
Did you know?
Someone who takes a long journey by plane might suffer from jet lag, a feeling tiredness that results from the person’s internal clocking at a different time than the timezone the person is in. For example, someone taking a plane trip leaves Toronto, Ontario, in Canada, at 1:15p.m. and arrives in Portland, Oregon, in the US, 6 hours later. The person’s internal biological clock says that the time is 7:15 p.m. However, Portland is only 3:15 p.m. When the traveler feels tired and ready to sleep, most people in Portland will just be making dinner!
Activity 1: Calculating Current Time in Another Time Zone
To understand how to calculate the time of day in different places using the world time zones.
- Chart of the 24 time zones in the world (can be found in most atlases)
- World History journals and pencils
Most Montessori teachers present this concept in Year 4 and present it in more detail in Years 5 and 6
Invite students to learn how to calculate time in other parts of the world
For Year 4 students, review lines of latitude and use the chart to illustrate them.
Demonstrate the globe.
Ask the students to find the line running through Greenwich, England at 0 degrees longitude. Explain that all time zones progress from this line and thatch 15 degrees or line of longitude represents 1 hour. Use the clocks on the chart to show that when it is noon at 0 degrees longitude, each time zone going east goes ahead one hour (plus) and each time one going west goes back 1 hour (minus).
Demonstrate the chart and discuss it with the students.
Invite the students to find a given place on the globe, then consult the chart to find the relevant time zone and determine how far it is from 0 degrees longitude. Repeat until all of the students have had a turn.
Ask the students what time it is in their time zone, then what time is it at that moment in. Another given time zone.
Encourage the students to practice with each other, giving and finding times in various world time zones.
Ask the students to use their journals to answer two questions: (1) If it’s 1:30 in the morning in Bombay, India, what time s it in Dallas, Texas, in the US? (2) If it’s 4 o’clock in the afternoon in Vancouver, British Columbia, in Canada, what time is it in Seattle, Washington, in the US?
YEARS 5 & 6
Define and discuss prime meridian, longitude, Greenwich Mean Time (GMT), Universal Time Coordinate (UTC), and International Date Line.
Demonstrate the globe.
Point to a location on the globe. Ask the students to determine what time it is in that zone and compare it to their own time zone. Do another few examples. Make sure to choose two places that are far apart on the globe but share the same time zone.
Discuss the Industrial Revolution and how it crated a need for standardizing time.
Introduce and explain the three ways of standardizing time (standard time, International Date Line, daylight saving) as ways humans manipulated time to meet their common needs.
If the students live in a country that uses daylight saving, talk about why it is used (to make better use of daylight hours) and what it feels like when the time changes (similar to jet lag, but lasting a shorter period of time for most people) If the students do not live in a country that uses daylight saving, unite the students to talk about why it might be used and imagine what it might be like.
Ask the students to use their journals to write a brief report summarizing the three ways of standardizing time and explaining how they were useful to humans.
Research and present a brief history of daylight saving time in a specific time of the world (e.g., the US, Canada, or France), noting why it was started and why it is still used.
Research and present a brief history of howGreenwich, England became the starting point for world time zones.
Research and prepare a list of the names and longitudes of all the time zones in the student’s country. (For example, time zones in the US, from west to east: Pacific, Mountain, Central, Eastern, Atlantic, Yukon, Alaska-Hawaii, Bering Strait.)
Write and act out a play showing what would happen to train or bus travel today without standard time.
Compare the likelihood of jet lag when traveling from Orlando, Florida, to Los Angeles, California, in the US by plane, bus, train, and car. Then compare likelihood of jet lag when traveling from Orlando, Florida, to Paris, France, by ocean liner and plane.
Research and write a short report about why UTC (Universal Time Coordinate) was adopted around the world and what it is ned for today.
Research and make a labeled poster illustrating the following timekeepers: mechanical clock, analog clock, digital watch, Add a note to each timekeeper, explaining how it contributed to more accurate timekeeping.