Use a large round fruit such as an orange or cantaloupe for the Earth and a smaller round fruit such as a cherry or kumquat for the moon. Pass the object you use for the moon between the light source for the sun and the object representing the Earth to demonstrate a solar eclipse. Pass the Earth object between the light source and the moon object to demonstrate a lunar eclipse. In an annular eclipse, the moon passes between the Earth and the sun at the farthest possible distance the moon can be. This position does not allow the moon to totally cover the sun, and you can see a tiny ring of light around the moon as it eclipses the sun.
In any eclipse demonstration, you need a concentrated light source to represent the sun. Use a flashlight, desk lamp or project the light from a slide projector or multimedia projector toward a classroom wall. Set the light source up as a stationary object. Ask students to hold the objects that represent the Earth and the moon and follow your directions to create the shadows necessary for the eclipse.
As noted above, you can use a large round fruit with a small round fruit to represent the Earth and moon. This makes a large visual the entire class can see. Using a dime for the moon and a half dollar for the Earth presents a much smaller demonstration useful for a single student. The Earth should be much larger than the moon. Use objects that you can suspend on a string to keep the students’ body parts from interfering with the shadows cast by whichever object is closest to the sun. Options include different sizes of sports or polystyrene balls, clay or papier-mache balls, balloons or cardboard circles. An inflatable globe makes an effective Earth model to demonstrate how the eclipse might appear at a specified location, and any small round object makes an effective moon for the display.
Various Web sources provide computerized models useful for classroom displays. Programs such as the Wolfram demonstration project allow you to manipulate variables such as the moon’s position and distance. Most computerized programs and Web pages also provide ideas for classroom lessons. The material may also include photographs of the eclipse in progress, allowing students to safely watch a solar eclipse without the need for eye protection.