Chapter 2 Lesson 2 "The Earth's Rotation and Time"

Materials:

• Sundial template.
• Worksheet, The Earth's Rotation and Time

Objective:

• Students will explain what causes day and night.
• Students will describe the standard time zones.

Anticipatory Set:* http://nist.time.gov/ is a site that keeps the exact time in the US. Ask the students what time is based on? Is it the same all over the globe? http://www.timeanddate.com/worldclock/ Why is it not the same time all over? Why have the clocks different from place to place. If you are standing anywhere on the globe at what time is the sun usually directly overhead or at its highest point in the sky?

To make the sundial students need to know their latitude. Have them find it using this map:

or this web address: http://www.geocode.com/modules.php?name=TestDrive_Eagle

If time is based on where the sun is in the sky, can we use the sun to tell the time? Show the students a sundial. Students will construct a sundial using the sundial template and these images.

Independent Practice:* (end of day 1) Students will read section 2, The Earth's rotation and Time. Students will complete the worksheet, The Earth's Rotation and Time.

Teacher Input:* Remind the students of the sundial and why it is different times around the globe. Next pose the simple question, why do we have day and night? So as the earth turns the sun lights up different parts of the Earth. Here is a look at where the sun is lighting up right now. http://images.google.com/imgres?imgurl=http://www.astronomy.villanova.edu/earthwatch/snap.gif&imgrefurl=http://astro4.ast.villanova.edu/pe/pe.htm&h=725&w=1022&sz=149&tbnid=2E4kTJXV1E4J:&tbnh=105&tbnw=149&hl=en&start=20&prev=/images%3Fq%3DInternational%2BDate%2Bline%26svnum%3D10%26hl%3Den%26lr%3D%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26sa%3DG or

http://astro4.ast.villanova.edu/pe/pe.htm click on or look for:

Motions: Time & Calendar from NIST
apparent v. mean solar time notes
time zones & international date line
Earthwatch; Screen shot notes
calendar & seasons

So, how many time zones each one hour different must their be on the face of the earth? Is there a way to know what time it is in Berlin, Germany right now? Show http://www.timeanddate.com/worldclock/converter.html Is the date the same everywhere on Earth?

Here are two maps (map1, Map 2) to help explain the different time zones. Point out the little places in Europe that are still on their own time. In fact a businessman in Asia and Europe may need a watch like this.

Do you think it is confusing to have 24 different times on earth? Have a student read the Did you know from P 32.

Is it the same day everywhere on Earth? Have you ever heard of the International Date Line? Show this picture and explain that this is not what is meant by that term. Instead use this picture to explain the date issue. It was not always in the same place when the United States bought Alaska in 1867 the line was moved to the west of it before that Alaska was on the East side of the line so that it would be the same day as Russia.

Show a picture of the time zones in the US and ask how the time zones affect things in the United States. For instance is the Today show live for you in Alaska?

Here is a rather neat way to look at the time zones: http://www.time-for-time.com/zonesus.htm

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Guided Practice:* Students will work together with their classroom teacher to complete the worksheet, The Earth's rotation and Time.

Check for Understanding:* Students will complete the quiz on lesson 2, "The Earth's Rotation and Time"

Duration:

30 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).

Alaska Performance Science Standards Addressed in this lesson:

• A.4 Earth
  Conduct research and make predictions about tides, weather, seasons, and phases of the moon and correlate these natural events to the motion of the Earth within our solar system.
• A.5 Forces of Nature
  Describe gravity as the force that governs orbital motion in the solar system and motion of the tides on the Earth, and describe light as radiation that travels in a straight line that can be reflected, refracted, or absorbed by matter.
• A.6 Motion
  Analyze how balanced and unbalanced forces act on familiar objects and predict or explain changes in motion that may (or may not) occur.
• A.7 Processes that Shape the Earth
  Use models to explain how large scale movements within the Earth's interior cause changes on the Earth's surface
• A.15 Local Knowledge
  Conduct research to learn how the local environment is used by a variety of competing interests including local plant and animal populations, individual families, the local community, and outside sources such as oil and mining companies, hunting groups, and tourists.