Materials: Handout, below

Standards

Laying the Groundwork
Discuss the meaning of the term horizon. (It is the line that appears to separate the Earth and sky.) Ask, What have you noticed about the sun and the horizon? Do you think the sun is the same height above the horizon at noon throughout the seasons? How could we explore this?

Warn students never to look at the sun; it is dangerous. Ask, How could we measure how high it is above the horizon without actually looking at it? One method is to hold out a hand out to block the sun and then use the other hand as a measuring tool.

Exploration

1. Drawing: Peter Alway

   Explain that early astronomers used parts of their hands to measure the angle of the sun above the horizon. Ask each student lift up an arm so it's parallel with the floor and hold out one finger. Scientists say that the width of a finger measures about 1 degree. Next, have them make a fist with the thumb on top. This measures 10 degrees. Explain that students now have tools to measure the angle of the sun above the horizon.
   
   
2. Practice measuring distant classroom items using your newfound tools.
   
   
3. Go outside on the winter solstice. Find a location where students have a fairly unobstructed view of the horizon to the south. (The sun's direct rays never hit farther north than the Tropic of Cancer, which is just south of Florida. So the sun in the U.S. and Canada always appears to our south.) Give them the following directions.
   
   

4. Try This! Find a partner classroom elsewhere in the country that wants to conduct the same exercise. What can you learn by comparing data from locations that are at different latitudes?

   Obscure the sun with your hands. Using the other hand, see how many fists and/or fingers you can fit between the horizon and sun.
   
   
5. Write the measurements (in degrees) for that date in your journals. Add other observations about the sun (for instance, the way it feels on the skin).
   
   
6. Exactly a month later, go outside, stand in exactly the same location, and do this again. As you do this throughout the winter and spring, you should begin to notice patterns.

Journal Questions

• When did the sun appear the highest? The lowest?
• What general statement can you make?
• What does this make you wonder about the progress of spring?

Extension

• Lesson: Heating Up: Direct and Indirect Sunlight >>
  Help students understand why the low angle of the winter sun gives us less heat energy than more direct sunlight in spring and summer.