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Earth Science Lesson Plans On Geologic Time Introduction
 To The Clock of Eras

Notes for the leader/teacher presenting The Earth Science Lesson Plans On Geologic Time Introduction: These lessons tell a story, but we recommend you choose your words carefully, not giving too much information or detail. This will give students the opportunity to think and express their own ideas. By encouraging students to share their ideas, you get the best insight as to what and how they are thinking and internalizing the information. Dialogue is included in bold and italics. Things you would do during the lesson are in CAPITAL LETTERS.

Prerequisites for the earth science lesson plans on geologic time introduction: Familiarity with analog clocks

Presentation of the earth science lesson plans on geologic time introduction:

  1. Review the standard clock. Key Concepts It keeps time in a circle so it is a circular timeline. The hands of the clock let us know the passing of seconds, minutes or hours. The numbers divide the clock into intervals—five minute intervals or hour intervals. This is a clock for telling time. (SHOW THE STANDARD CLOCK.) Look at the hands on the clock. This hand shows the passage of seconds. We call it the “Second Hand.” This one shows the passing of minutes. We call it the “Minute Hand.” This one shows us the hour; we call it the “Hour Hand.” Let’s review how a clock measures time. The second hand ticks for every second that passes: 60 in a minute. Then the minute hand moves one tick for every minute: 60 in an hour. It takes the minute hand one hour to go all the way around the clock. The hour hand moves once every hour and tells us the hour that the other hands are working in, like the two o’clock hour, the four o’clock hour and so on. It takes the hour hand twelve hours to go around once. Look at the numbers on the clock. They divided the time into sections-intervals-of five minutes. That makes it faster for us to decide how many minutes or hours have passed.
  2. Demonstrate the Clock of Eras Key Concepts It shows time that has already passed. It shows the time that has passed since the Earth was formed. The intervals show us time periods when the Earth looked a certain way and certain animals and plants lived on it. The Earth has not always looked the way it does now. This is a new clock. (SHOW THE CLOCK OF ERAS.) There are a few differences between this clock and the clock we use for telling time. The intervals don’t show time that is passing now. They show time that has already passed. This clock hand began to move when the Earth was just forming. This clock represents the time the Earth has been in existence, about 4.5 billion years. So one hour would represent 375,000,000 years passing. On our standard clock we have second hands that measure seconds, minute hands that measure minutes, and hour hands that measure hours. (TAKE THE LOOSE HAND FOR THE CLOCK OF ERAS.) On this clock our hand measures Eras. As it passes around the clock, it colors the clock as it marks off the eras. Each new color represents a new era. The colors on the clock will remind us of how the earth was forming and how life was taking shape on the planet.

Follow up for earth science lesson plans on geologic time introduction:

  1. Have students color and/or cut out parts of the clock and place them in the proper order on the template.
  2. Older students could measure the angles and recreate the clock using a protractor.
  3. Have students practice moving the Era Hand around the clock: Saying how much time has passed as it passes each hour. Matching the names of the Eras to the sections on the Clock.

Done with earth science lesson plans on geologic time introduction?
Click here for the next lesson in the series, The Hadean Time

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