Who set the first clock?

Who set the first clock?

Lesson narration:
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DISCUSS:

How do you think the very first clock got set, when there was no other clock to look at?

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DISCUSS:

Long ago, people did not have the concept of hours or minutes. Someone had to come up with these ways to divide a day into parts.

How would this week have gone wrong for you if you could only measure time in days?

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DISCUSS:

Try counting like an Egyptian! Use your thumb to count all of the finger segments on that same hand.

How many finger segments do you have on one hand?

Reveal answer...

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DISCUSS:

So why do you think there are 24 hours in a day?

See what we thought...

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DISCUSS:

What happens to the shadows as time passes?

How could you use shadows to measure the Sun's position?

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# Extensions
Below are ideas for extending this topic beyond the activity & exploration which you just completed.
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#Why are the shadows moving so fast?

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Answer:

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Which direction are you facing when you sit in this chair? North, South, East, or West?

Hint: Watch the shadow and think about what it tells you about the Sun’s movement. Click here to play video

Here's how we figured it out:

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How is the movement of the clock’s hands like the movement of the shadow?

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Answer:

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# Activity: Moving Shadow Game

Here’s a game to play outside on a sunny day. Find a place where the shadow of a building or wall makes a straight line. Mark that line with chalk.

Ask students to predict where the shadow will be in 15 minutes. Mark their guesses with other colors of chalk.

In 15 minutes, mark where the shadow ended up. How close were the guesses? Try again to see if you can do better.

This game is best when the Sun is low in the sky. Don’t play at noon, when the Sun is high in the sky.

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north


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one of four main directions; when you face north, west is to the left and east is to the right
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south


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one of four main directions; if you are facing north, it is the direction behind you
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east


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one of four main directions; if you are facing north, it is to the right
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west


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one of four main directions; if you are facing north, it is to the left
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sundial


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a tool that tells time by using the changing direction of shadows caused by the Sun's movement across the sky
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Other
clock by TBIT / cropped, adjusted color
Lesson narration:

Activity Prep

Print Prep

In this lesson, students will learn why our ancestors divided the day into hours and how clocks measure the Sun’s apparent movement. In the activity, Make a Shadow Clock, students make their own sundials. First, students use flashlights indoors to understand how the position of the light affects the time shown on the clock. Then, students take their shadow clocks outside to see how the position of the Sun can tell them the time of day.

Preview activity

Exploration

20 mins

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