All lessons › Challenge: Moon, tides and eclipses › Lesson 1
Australian primary science · Years 5–6 (challenge) · Lesson 1 of 3
Why does the Moon change shape?
Inquiry question: Why do we see different shapes of the Moon across a month?
Check practical materials
Using a model
What students learn
The Moon doesn’t make its own light; half of it is always lit by the Sun. As the Moon orbits Earth over about a month, we see different amounts of its lit half. These are the phases.
Success criteria
- I can explain why half the Moon is always lit.
- I can use a model to show new moon, quarter moon and full moon.
- I can explain why the phases are not caused by Earth’s shadow.
Preparation and materials
Before this lesson: Students can model day and night with a torch and a ball (Earth and the Sun, lesson 2).
- Torches (or one bright lamp with the shade removed, for a whole-class model) — 13 (or 1 lamp)
- Small balls on a stick: polystyrene balls on pencils, or oranges on skewers (kept from Earth and the Sun) — 13
- A room that can be darkened — 1
Teacher setup
- Darken the room as much as you can.
- Try the model yourself: hold the ball at arm’s length and turn slowly on the spot with the lamp behind you to one side.
- If using skewers, push the sharp end well into the fruit or tape over it.
Safety and adaptations
- Don’t shine torches into anyone’s eyes.
- Hold sticks and skewers pointing upwards and walk, don’t run, in the darkened room.
- Never look straight at the real Sun.
Review your school policies and curriculum requirements before teaching.
How to investigate
The lesson sequence should leave pupils with evidence to interpret, not only an activity to finish.
- Write a hypothesis: “If the Moon’s phases are caused by ___, then in the model we will see ___.”
- In pairs (or as a class), turn slowly anticlockwise holding the Moon ball and stop at eight positions.
- At each position, draw the lit shape you see and where the Moon is compared with the Sun.
- Test the ‘Earth’s shadow’ idea: at quarter moon, is your head’s shadow on the ball?
- Use your drawings to explain the phases.
Teacher modelling prompt
Turn on the lamp and darken the room. Hold the ball at arm’s length in front of you, slightly above your head. Your head is Earth. Think aloud: “The lamp is the Sun. The ball is the Moon. Look: the half of the ball facing the lamp is always lit. When I hold it towards the lamp, I see the dark side: new moon. I turn a quarter: I see half of the lit side, a quarter moon. Turn with my back to the lamp, holding the ball above my head’s shadow: I see the whole lit side, full moon.”
Record and explain evidence
Recording question: Why do we see different shapes of the Moon across a month?
| Position | Where the Moon is (towards Sun, side, away from Sun) | Shape I see (draw) | Phase name | Is Earth’s shadow on the Moon? |
|---|---|---|---|---|
| ________________ | ________________ | ________________ | ________________ | ________________ |
Example recording headings; record actual observations, including inconclusive results.
Discussion prompt
Use what the model showed at quarter moon to decide.
Check understanding
What should pupils know? Why does the Moon seem to shine?
Explain with evidence: At full moon, where are the Sun, Earth and Moon? Explain how that makes the whole face look lit.
Apply the idea: Tonight there is a full moon. About how many days until the next new moon? Explain.
Teacher answer guidance and saved classroom work are available through the main lesson experience where supported.