Teacher Information Sheet #1: Sample Classification Teacher Information Sheet #2: Measuring Time Teacher Information Sheet #3: Historical Events Scoring Guide Teacher Information Sheet #4: Chronology of Historical Events Teacher Information Sheet #5: Canadian Perception of Time

PDF file for all of Grade 9 Unit 1 Teacher Information Sheets

The sun, moon, planets and stars have provided a reference for measuring the passage of time throughout our existence. Ancient civilizations relied upon the apparent motion of these bodies through the sky to determine seasons, months and years.

Little is known about timekeeping in prehistoric eras, but records and artifacts reveal that, in every culture, some people were preoccupied with measuring and recording the passage of time. Ice-age hunters in Europe over 20,000 years ago scratched lines and gouged holes in sticks and bones, possibly counting the days between phases of the moon. Five thousand years ago, Sumerians in the Tigris-Euphrates valley (today's Iraq) used a calendar that divided the year into 30-day months, divided the day into 12 periods (each corresponding to two of our hours), and divided these periods into 30 parts (each like four of our minutes). There is no written record of the origin of Stonehenge, built over 4,000 years ago in England, but its alignments show its purposes apparently included the determination of seasonal or celestial events, such as lunar eclipses and solstices.

The earliest Egyptian calendar was based on the cycles of the moon. When they realized that the "Dog Star" in Canis Major, which is now known as Sirius, rose next to the sun every 365 days, the Egyptians developed a 365-day calendar (ca. 4236 B.C.).

In Babylonia (today's Iraq) a year of 12 alternating 29-day and 30-day lunar months was observed before 2000 B.C., giving a 354-day year. In contrast, the Mayans of Central America relied not only on the sun and moon, but also the planet Venus, to establish 260-day and 365-day calendars. This culture flourished from 2000 B.C. until about 1500 A.D. They left records indicating the belief that the creation of the world occurred in 3113 B.C. Their calendars later became portions of the great Aztec calendar stones. Other civilizations, including our own, have adopted a 365-day solar calendar with a leap year occurring every fourth year.

Eventually, people found a need for knowing the time of day. Great civilizations in the Middle East and North Africa initiated clock-making as opposed to calendar-making (5000-6000 years ago).

Sun Clocks

The Egyptians formally divided their day into parts similar to what we call hours. Obelisks (slender, tapering four-sided monuments) were built as early as 3500 B.C. Their moving shadows formed a kind of sundial, enabling people to partition the day into two parts separated by noon. They also showed the year's longest and shortest days when the shadow at noon was the shortest or longest of the year.

Another Egyptian shadow clock or sundial, possibly the first portable timepiece, came into use around 1500 B.C. to measure the passage of "hours." This device divided a sunlit day into 10 parts plus two "twilight hours" in the morning and evening. When the long stem with five variably spaced marks was oriented east and west in the morning, an elevated crossbar on the east end cast a moving shadow over the marks. At noon, the device was turned in the opposite direction to measure the afternoon "hours."

In the quest for more year-round time pieces, sundials evolved from flat horizontal or vertical plates to more elaborate forms. One version was the hemispherical dial, a bowl-shaped depression cut into a block of stone, carrying a central vertical pointer and scribed with sets of hour lines for different seasons.

Water Clocks

Water clocks were among the earliest timekeepers that did not depend on the observation of celestial bodies. One of the oldest was found in the tomb of Amenhotep I, buried around 1500 B.C. Later named clepsydras ("water thief") by the Greeks, who began using them about 325 B.C., these were stone vessels with sloping sides that allowed water to drip at a nearly constant rate from a small hole near the bottom. Other clepsydras were

cylindrical or bowl-shaped containers designed to slowly fill with water coming in at a constant rate. Markings on the inside surfaces measured the passage of "hours" as the water level reached them. These clocks were used to determine hours at night, but may have been used in daylight as well.

More elaborate and impressive mechanized water clocks were developed between 100 B.C. and 500 A.D. by Greek and Roman horologists and astronomers. The added complexity made the flow more constant through the regulation of pressure, and provided fancier displays of the passage of time. Some water clocks rang bells and gongs, other opened doors and windows to show figurines, and others moved pointers, dials, and astrological models of the universe.

Because the rate of flow of water is very difficult to control, clocks based on that flow could never achieve true accuracy. People were naturally led to other approaches.

A Revolution in Timekeeping

In Europe during most of the Middle Ages (roughly 500 to 1500 A.D.), technological advancement in timekeeping was at a virtual standstill. Sundial styles evolved, but did not move far from ancient Egyptian principles.

Then, in the early-to-mid 14^th century, large mechanical clocks began to appear in the towers of several large Italian cities. These public clocks were weight-driven and regulated by a verge-and-foliot escapement. Verge-and-foliot mechanisms reigned for more than 300 years with variations in the shape of the foliot. All had the same basic problem: the period of oscillation for this escapement depended heavily on the amount of driving force and the amount of friction in the drive. Like water flow, the rate was difficult to regulate.

Another advance was the invention of spring-powered clocks between 1500 and 1510 by Peter Henlein of Nuremberg. Replacing the heavy drive weights allowed clocks and watches to be smaller and more portable.

Accurate Mechanical Clocks

In 1656, Christian Huygens, a Dutch scientist, made the first pendulum clock, regulated by a mechanism with a "natural" period of oscillation. Huygens' pendulum clock had an error of less that one minute per day, the first time such accuracy had been achieved. His later refinements reduced his clock's errors to less than ten seconds a day.

Around 1675 Huygens developed the balance wheel and spring assembly, still found in some of today's wrist watches. This improvement allowed 17^th century watches to keep accurate time to within ten minutes a day. And in London in 1671, William Clement began building clocks with the new "anchor" or "recoil" escapement, a substantial improvement over the verge because it interfered less with the motion of the pendulum.

Refinements led in 1889 to Siegmund Riefler's clock with a nearly free pendulum, which attained accuracy within a hundredth of a second a day and became the standard in many astronomical observatories. A true free-pendulum principle was introduced by R.J. Rudd in about 1898, stimulating the development of several free-pendulum clocks.

Quartz Clocks

Quartz crystal clocks were developed in the 1930s and 1940s, improving timekeeping performance far beyond that of pendulum and balance-wheel escapements.

Quartz clock operation is based on the piezoelectric property of quartz crystals. If you apply an electric field to the crystal, it changes its shape, and if you squeeze it or bend it, it generates an electric field. When put in a suitable electronic circuit, this interaction between mechanical stress and electric field causes the crystal to vibrate and generate a constant frequency electric signal that can be used to operate an electronic clock display.

Quartz crystal clocks were an improvement because they had no gears or escapements to disturb their regular frequency. Even so, they still relied on a mechanical vibration whose frequency depended critically on the crystal's size and shape. However, no two crystals can be precisely alike, with exactly the same frequency. Such quartz clocks continue to dominate the market because their performance is excellent and they are inexpensive.

Figures

	20th Century	1600-1900	900-1599	1-899	BC
Where he/she lived	1 point	2 points	3 points	4 points	5 points
When he/she lived	1 point	2 points	3 points	4 points	5 points
What caused the person to do what he/she did?	1 point	2 points	3 points	4 points	5 points
Why he/she is significant?	2 points	4 points	6 points	8 points	10 points

• Television and radio programs are scheduled down to the last second.
• Our language contains many expressions that show the value we place on time. For example, time is money, lost time, wasting time, saving time, time on your hands, etc.
• Most public buildings have a clock in a prominent place.
• Airplanes, buses and trains all run according to a set schedule and people get very upset if they are not on time.
• Most people in our country wear watches.
• Junior and senior high school classes are organized according to a rigid schedule.

• When there are six or seven facts and examples on the chalkboard, begin classifying them. Have the class tell you which facts belong together. The facts relating to the generalization "Canadian society is very time conscious" can be classified into categories as shown below.

Category 1
• Our language contains many expressions that show the value we place on time-time is money, lost time, wasting time, saving time, time on your hands, etc.

Category 2

Most people in our country wear watches.

Then, for each group of facts, ask the class to identify the main idea. Below are the main ideas for the categories in this example:

Category 1 - The speech of most Canadians reflects a preoccupation with time.

Category 2 - Many aspects of our life operate according to rigid schedules.

Category 3 - Clocks and watches are all around us. · Recall that the essay topic sentence in this exercise was "Canadian society is very time conscious." Each of the main ideas above can serve as a topic sentence for the paragraphs that follow. The detailed facts identified earlier can be used to support the topic sentences for the essay.

Below is a point form outline of an essay on the theme "Canadian society is very time conscious."

Topic sentence	Canadian society is very time conscious.
Supporting evidence #1	The speech of Canadians reflects a preoccupation with time.
Facts and examples that illustrate supporting evidence #1	Language contains many expressions that show the value placed on time-time is money, lost time, wasting time, saving time, time on your hands, etc.

Supporting evidence #2	Many aspects of our life operate according to rigid schedules.
Facts and examples that illustrate supporting evidence #2	Junior and senior high school classes are organized according to a rigid schedule. Airplanes, buses and trains all run according to a set schedule. Television and radio programs are scheduled down to the last second.
Supporting evidence #3	Clocks and watches are all around us.
Facts and examples that illustrate supporting evidence #3	Most public buildings have a clock in a prominent place. Most people in our country wear watches.

• Explain to students that you have just developed a point form outline for an essay on the theme "Canadian society is very time conscious." Ask each student to select one of the pieces of information about time that they have learned and to use a similar process to prepare an outline that is then to be developed into a short essay. An essay that includes an opening theme statement, two or three supporting paragraphs and a conclusion is appropriate for early grade nine.