Before class, find an outdoor route extending in a straight line 63m long, from where the model Sun will be (the exercise ball), to where the model Earth and Moon will be. If a gravel field is used, an orbit path can also be traced on its surface with a stick or heel of a shoe.
This activity can be shortened by making the Earth/Moon model, then looking out of the window to see where the exercise ball 'Sun' would be.
In the classroom, show students the Sun (exercise ball), and tell them that if the Sun is this large, Earth is only 5.5mm wide, and the Moon is only 1.5mm wide!
Distribute the rulers, Earth/Moon images and modelling clay to student pairs. Ask each group to make a model Earth (5.5mm in diameter) and Moon (1.5mm in diameter) from the modelling clay, using the image to guide their colour choice. Students will likely make them too large to start - prompt them to keep removing clay until they are the correct size. Then ask students to tape their model Earth and Moon onto the cardstock 15cm apart (without squishing them too much!).
Tell students that using these model sizes, to place them at the correct distance from the Sun, we need to go outside! Take the students outside with the model Sun, their Earth and Moons, as well as a metre stick/tape measure.
Place the Sun (exercise ball) on the ground, and tell students that, to scale, the Earth and Moon will be 63 metres away from this Sun. Lay down a metre rule/tape measure, so that students can roughly gauge how long their stride needs to be to pace a metre. Then as a class, pace 63m from the Sun. Place their model Earth at this spot. Look back at the Sun to see how far away it is and how much empty space there is between the Earth and the Sun.
With the students watching, trace a line in the gravel (with a stick or shoe heel) part way around the Sun, always at 63m or thereabouts, showing about ¼ of the orbit of the Earth, then point out how it will extend beyond the gravel field. Earth takes a year to orbit the Sun. Point out where each season would be with each ¼ of the way around the orbit.
Then ask students to walk part way along the Earth’s orbit, while also rotating their cardstock so that the model Moon orbits the Earth. The Moon takes a month to orbit the Earth.
Before heading back to the classroom, use the model to emphasize how far away the Sun and Earth are, and even how far the Earth and Moon are from each other, and how much empty space there is in-between. The Artemis mission took four days to reach the Moon!
| Object |
Scaled diameter |
Scaled distance |
| Sun |
60cm (exercise ball) |
|
| Earth |
5.5mm |
63m from the Sun |
| Moon |
1.5mm |
15cm from the Earth |
See this webpage for calculating Sun-Earth-Moon scaled diameters and distances apart: https://www.dunlap.utoronto.ca/~du/solarsystem.html
Optionally, trace out the orbit of the Earth in the gravel (or make a chalk line), walking around the model Sun but always staying 63m (or thereabouts) from it. Tell students that a season passes as the route takes you ¼ of the way around the Sun (then another season if you able to walk ½ way around the Sun). Complete as much of the orbit as possible.
Before heading back to the classroom, use the model to emphasize how far away the Sun and Earth are, and in turn how far the Earth and Moon are from each other, and how much empty space there is in-between.
As an alternative to placing one Earth and Moon, place the Sun, then ask students to pace 63m away, all in different directions, taking their model Earth and Moon. When the students each reach their spot 63m away, tell them to place their Earth. Then place their Moon, 15cm from their Earth. Each of the Earths show a different part of the Earth’s orbit around the Sun. Walk between the student groups, tracing a path if possible, to show the orbit of the Earth around the Sun. Tell students that while the Earth orbits the Sun, the Moon is also orbiting the Earth.
