Currently there are 24 Global Positioning Satellites (GPS) circling around the earth.  Signals from these satellites are received by millions of people everyday.

Construct a model of what the satellites might look like using the following materials.

For each student:  (approx. cost, $3 per student)
1 Large Styrofoam ball
24 small foam balls
24-pipe cleaners of varying length (floral wire may also be used)

1. If desired, the large balls may be colored with markers or painted to resemble the earth.
2. Push one piece of wire or pipe cleaner into each small foam ball.  These represent the 24 satellites in space
3. Then push each piece of wire with a ball on it into the larger ball (earth).

This model represents the 24 GPS satellites in space that orbit the earth daily.  Models may be hung from the ceiling for additional observation.

Tips:

? If 24 foam balls cannot be provided for each student, students may work in pairs or groups.
? One large ball may be colored by the teacher and students each allowed to make a “satellite” to position on the “earth”.
? Another tip is to use only 4 foam balls per large ball.  This would show that of the 24 satellites, only 4 are accessible at any one time.
? Balls can be purchased at most discount or craft stores.