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9-12 > Technology
Grade level: 6-8 Subject: Technology Duration: One class period (plus)
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Lost in Time

Students will understand the following:
1. Our perception of passing time is not always accurate.
2. In order to calculate time accurately, we require time-measuring instruments.

For this lesson, you will need:
For each pair of students, a watch or clock

1. Ask students to imagine that there were no watches, clocks, or announcements of time on radio or television. Do they predict that they would be able to estimate the time of day accurately, using only their own perceptions of passing time?
2. Tell students they are going to participate in an experiment to test their predictions.
3. Have students pair up for the experiment.
4. One partner will go a whole weekend or vacation day without a watch or clock. He or she will not be permitted to use television, radio, or any other means to help find the time of day. As the day starts and progresses, that partner will periodically tell the other student what time he or she thinks it is. The other student will record the estimates and also the actual time each estimate is made.
5. On a subsequent weekend or vacation day, the partners will switch places.
6. Back in class, discuss with students how well their predictions correlated to actual time. Did they tend to estimate earlier or later than the actual time? Was it difficult to be without an instrument to measure time? Why or why not?
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Have students research and prepare presentations on aspects of the history of time measurement.
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Discussion Questions

1. Discuss the idea of continuing to use sextants, stars and clocks for navigation when GPS technology is available. Extend the discussion to include learning how to do mathematics when a calculator is always at hand and learning to spell correctly when a computer spell check can be used.
2. Discuss the impact of England being the country to "perfect" the chronometer. How might global relations be different today if another country, China for example, had had navigational superiority.
3. Discuss the idea that "necessity is the mother of invention" in light of the Hamilton Watch Company of Lancaster, Pennsylvania. They developed a very precise chronometer because there was a naval need for one during World War II. Do inventions and improvements only happen when there is a real need for them?
4. Discuss how our current day would change over time if NASA had not discovered that the Earth's rotation is slowing down and as a result, a leap-second must be added to keep the day on track. The Earth is slowing down by one one-thousandth of a second per day. Would you notice a change in the day in your lifetime if the slowing was not corrected?
5. Discuss the idea that navigation will fuel the next generation of chronometers. Is the "fuel" really navigation or is it the desire for military superiority?
6. Discuss whether athletic timing today is too precise. If humans are the competitors should we measure events within human limitations or should we use our technology to measure actual distances between competitors as accurately as possible? Keep in mind that differences of millions of dollars in product endorsements often separate first and second place athletes.
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You can evaluate students on their experiments using the following three-point rubric:
  • Three points:results clearly and correctly recorded

  • Two points:results recorded, but lacking in clarity

  • One point:failure to record results

You can ask your students to contribute to the assessment rubric by determining a minimum number of times during the day partners should estimate the time and record the actual time.
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Just a Sec!
We’ve all heard someone say, “Wait a second.” Discuss with students how much time a second really is. You might bring out in conversation that it’s enough time for a basketball team to score a winning basket; it can mean meters in track or swimming sprints; and it can mean more than 10 meters in cycling events. Ask students if they think they can jump in the air or say their own names in one second. With the class, complete a list of activities they think can be done in one second (e.g., words spoken, fingers drummed, meters walked or run). Have them try out the activities to see if they were right. Then have them perform the same activities over a period of five seconds. Can they do five times as much? Discuss whether students have changed their ideas about what can be done in a second.

Calculate human reaction time with the class. On the words “on your mark, get set, go,” have students take turns clicking a stopwatch on and then off as quickly as they can and note the amount of time it took each student. Average the times to get an average human reaction time. If you do not have a stopwatch, you can calculate reaction time in the following way. Have a student hold a ruler marked in centimeters between thumb and index finger. The ruler should be held vertically, with the zero centimeter mark in line with thumb and finger. Have the student let go of the ruler so that his or her partner can catch it by pinching it between thumb and finger. Measure the number of centimeters the ruler has fallen.

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Suggested Readings

Relativity in the Palm of Your Hand
Neil Ashby, Mercury, May 1996
Atomic clocks, which rely upon atoms' inherent natural abilities to maintain reliable standards of time, are set in space and monitored by 24 satellites that orbit Earth and which compose the Global Positioning System. These standards, by which our own watches and clocks are set, reflect to us the universal principles of relativity.

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Frequently Asked Questions Regarding Time and Frequency Issues
If you wonder exactly when the next millenium begins or why we need leap seconds, then consult the FAQs of the National Institute of Standards and Technology (NIST), the official organization for the establishment of time scales.

A Brief History of Time
Using this hypertext document, let students find why we invented the calendar, and why there are so many different kinds of calendars used around the world.

Sundial Links
Using any one of the "Sundial Generator" links available at this website, challenge your students to explain the annual and daily solar cycles.

The Directorate of Time, U.S. Naval Observatory
Do you want to know what time it is NOW? It’s not as easy as you think to get the right answer.

Black Holes and Neutron Star
Has “Lost in Time” piqued your curiosity about time travel and relativity? Then find your way to this website authored by NASA's astrophysicist, Robert Nemiroff.

The Center for Biological Timing
Find a variety of hands-on student projects related to our biological clocks as well as an interesting interactive textbook on the subject.

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Click on any of the vocabulary words below to hear them pronounced and used in a sentence.

speaker    longitude
Definition:Angular distance on the earth's surface, measured east or west from the prime meridian at Greenwich, England, to the meridian passing through a position, expressed in degrees (or hours), minutes, and seconds.
Context:Until the eighteenth century sailors had no way to figure out their longitude. The lucky ended up only a few hundred miles off course, the unlucky ones lost at sea.

speaker    chronometer
Definition:An exceptionally precise timepiece.
Context:The race was on for the perfect clock, what watchmaker Jim Michaels calls a chronometer.

speaker    biomechanists
Definition:Scientists who study the mechanics of a living body, especially of the forces exerted by muscles and gravity on the skeletal structure.
Context:Training hard is only the first step. To win the gold today these athletes need the help of physiologists, biomechanists and engineers who review every moment of the race.

speaker    drafting
Definition:Staying close behind another vehicle to take advantage of the reduced air pressure in its wake.
Context:Also new is an ultra-small front wheel which allows for better drafting.

speaker    passive
Definition:Receiving or subjected to an action without responding or initiating an action in return.
Context:We're measuring Mark's passive resistance. We're trying to figure out in a nice streamline position how much resistance he has from the water.

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This lesson plan may be used to address the academic standards listed below. These standards are drawn from Content Knowledge: A Compendium of Standards and Benchmarks for K-12 Education: 2nd Edition and have been provided courtesy of theMid-continent Research for Education and Learningin Aurora, Colorado.
Grade level:9-12
Subject area:technology
Understands the interactions of science, technology and society.
Knows that science often advances with the introduction of new technologies and solving technological problems often results in new scientific knowledge; new technologies often extend the current levels of scientific understanding and introduce new arenas of research.

Grade level:9-12
Subject area:technology
Understand the interaction of science, technology and society.
Knows that science and technology are pursued for different purposes: scientific inquiry is driven by the desire to understand the natural world and seeks to answer questions that may or may not directly influence humans; technological design is driven by the need to meet human needs and solve human problems and has a more direct effect on society than science because its purpose is to solve human problems, help humans adapt and fulfill human aspirations.

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Karen K. Kennedy, chemistry and physics teacher, T.C. Williams High School, Alexandria, Virginia.
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