Follow the Sun for a Day
Creating an Earth/Sun Model
 Time 1 period, then a few minutes each hour through the day Materials clear 2-quart bowl, large sheet of white paper taped to a piece of cardboard or other rigid item, sharp pencil, erasable marker, compass, crayons or colored pencils Teacher Background Standards

Overview
Students create a simple model of the Earth and sun as seen from space. They use it to explore the sun's apparent movement across the sky over the course of a day. They begin to understand that the sun appears to move west, but that it is the Earth's rotation toward the east that causes this phenomenon. This lays the groundwork for understanding Mystery Class longitude clues.

Preparation
Conduct this activity on a sunny day.

Laying the Groundwork
Invite students to imagine they are far out in space and can see the Earth and our sun. Ask, What would you expect to see happening and why? Make four different drawings, to show what you'd see during a day. Once students have completed this, ask, What questions do you have? Save these for students to revisit during and after this activity.

Exploration
1. Make an X in the center of the paper to represent our Earth.

2. Take the materials outside. Find a level surface for the paper. Make sure the location receives sunlight all day.

3. Place the bowl upside down on the paper. Ask students to imagine it's our atmosphere. Mark an x on the center of the bottom of the bowl with the overhead marker. Make sure the x on the paper is lined up under the x on the bowl. Trace the edge of the bowl onto the paper to make it easier to line up.

4. Have students use a compass to determine North for your location. Once they've reached consensus, they should mark North on the paper and the bowl.

5. Each hour, have a student touch the side of the clear bowl with the tip of the pencil so the shadow of the pencil's tip falls on the X on the paper. Have a partner make a dot on that spot with the marker. (Putting a number beside each dot will help students recall the order in which they made observations.) After each dot goes on, ask, Where do you predict the next dot will be? Explain your thinking. Which direction does the sun appear to be moving?

Note: To get accurate results, the bowl must sit in the same location and be lined up in the same way for each hourly reading.

Making Connections
Discussion and journaling questions
:

• What patterns did you notice over the course of the day?
• How would you explain them?
• What general statement(s) could you make about the daily movements of the sun and Earth?
• What questions do you still have?
 What to Expect The Earth rotates counterclockwise, toward the east. However, the sun appears to be moving west over the course of a day. Students' earlier explorations should have revealed that the sun does not move. Rather, it is the Earth's rotation that makes the sun appear to move west. The Living Earth® image is a composite of Earth satellite imagery developed by The Living Earth, Inc. From: The Earth and Moon Viewer

Assessment
Once students have completed the exploration, ask them to revise the drawings they made during Laying the Groundwork. They can either create new ones or use another color to make changes. Their responses to the discussion and journaling questions along with the changes in their drawings should reveal an enhanced understanding of the daily Sun-Earth relationship. Also see these assessment tasks:

 Criteria: Student can explain via words, models, drawings, or actions: Beginning Developing Mastery The orientation of the Earth and Sun throughout the year. How the tilt of the Earth combined with its revolution around the sun affects day length (photoperiod) and the angle (intensity) of sunlight at in different seasons. How differences in photoperiod and angle of sunlight affect seasonal temperatures. How day length varies with latitude during different seasons. The characteristics of the solstices and equinoxes in terms of the Earth/Sun orientation, daylength, and angle of the Sun in relation to Earth. How and why shadows change over the course of the year.