Divide the class into groups of three or four. Give each group the materials to make their own model of the Sun-Moon-Earth system.
Take one cardboard tube and make a series of small (2-cm deep), even, vertical cuts around the circumference of each end.
Bend the cut pieces out at each end and then stand the tube upright. The cut edges should fan out like a flower (Image 6).
Using adhesive tape, fasten one end of the cardboard tube to the cardboard strip to create the base of the model. The tube should be at least 30 cm from one end of the cardboard strip.
Using tape or glue, attach the larger ball to the top of the tube. This ball represents the Earth (Image 7).
Cover the smaller ball with aluminium foil, with the shiny side on the outside. This will be the Moon.
Insert one end of the wire into the top of Earth so that the wire is vertical.
Measure approximately a finger’s length along the wire and bend the wire here at a right angle, creating a horizontal arm.
About halfway between the Earth and the far end of the cardboard strip, measure a finger’s length along the wire and bend it again. This time bend it downwards at a right angle, towards the cardboard base.
Insert the other end of the wire into the "Moon". The Moon’s equator should be at the same height as the Earth’s equator (Image 8).
Balance the torch on a stack of books or magazines at the opposite end of the cardboard strip from the “Earth”. Make sure the height is correct: the middle of the torch beam should hit Earth’s equator.
If the beam is too diffuse, attach the second cardboard tube to the end of the torch to direct the light. Ensure that the beam directly hits the nearest half of the Earth and the Moon. If the beam is not bright enough, move the stack of books closer (Image 9).
Now students will use their models.
Begin by asking your students if they have ever seen an eclipse. Was it a solar or a lunar eclipse? Explain that solar eclipses are much less common than lunar eclipses, but today they will be lucky enough to see both!
Create a solar eclipse: Stand facing the torch and swing the wire around until the Moon casts a shadow on the Earth; if necessary, dim the lights in the room. The Moon is now positioned between the Earth and the Sun and is blocking the “sunshine” for some people on Earth. Point out that only people directly in the shadow will see a complete eclipse of the Sun. You can show how the shadow moves by slowly rotating the wire (Image 10).
Now create a lunar eclipse: Stand facing the torch and swing the wire so that the Moon is behind the Earth. No light should be hitting the Moon: the Earth is between the Sun and the Moon, casting a shadow over the entire Moon. Explain that unlike during the solar eclipse, the entire "night" side of Earth can see the lunar eclipse (Image 11).