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Science Lesson Kit · Teacher Resource

Moon Phase Modeling: Why Does the Moon Seem to Change Shape? — 5E Lesson Plan

Space Science · 50 minutes

Grade 4

5E lesson flow

  1. 01

    Engage

    6 min

    Teacher Does

    Show photographs of several Moon phases and ask whether the Moon itself changed shape.

    Students Do

    Describe the visible illuminated shapes and propose explanations.

    Ask

    • What stays the same about the Moon? What seems to change?

    Look For

    Difference between actual object shape and illuminated appearance.

  2. 02

    Explore

    15 min

    Teacher Does

    Set one lamp as the Sun and guide students through several Moon-ball positions.

    Students Do

    Keep their viewpoint at Earth, move the Moon ball, and sketch the visible lit portion at each position.

    Ask

    • Which half is lit by the lamp?
    • How much of that half can you see?

    Look For

    Lit half faces lamp; visible fraction changes.

  3. 03

    Explain

    9 min

    Teacher Does

    Introduce phase, orbit, illuminated, crescent, gibbous, and viewpoint.

    Students Do

    Connect model positions to phase descriptions.

    Ask

    • What causes the phase pattern in this model?

    Look For

    Changing Sun-Earth-Moon geometry and viewpoint.

  4. 04

    Elaborate

    13 min

    Teacher Does

    Present the Earth-shadow misconception and a not-to-scale model question.

    Students Do

    Use the model to test the shadow idea and identify model limits.

    Ask

    • Can you make a crescent without Earth blocking the light?
    • What does our model exaggerate?

    Look For

    Yes; ordinary phases do not require Earth's shadow. Distances and sizes are not to scale.

  5. 05

    Evaluate

    7 min

    Teacher Does

    Give a new Moon-position card.

    Students Do

    Shade the illuminated half, sketch the Earth-view appearance, and explain their reasoning.

    Ask

    • What evidence from the model supports your sketch?

    Look For

    Consistent illumination geometry and viewpoint reasoning.

Student goal

I can use a model to explain how the Moon's position changes the illuminated part we see from Earth.

Learning objectives

  • Use a physical model to explain that the Sun illuminates half of the Moon while our view of the lit half changes.
  • Connect Moon positions in the model with visible phase patterns such as crescent, quarter, gibbous, and full.
  • Use evidence from the model to distinguish ordinary Moon phases from Earth's shadow during a lunar eclipse.

Materials

  • One bright lamp or fixed flashlight for teacher demonstration
  • Small foam balls on sticks
  • Darkened area of classroom
  • Moon-position cards
  • Recording sheet

Before class

  • Place the lamp where students can move around it safely.
  • Use a bright but cool light source; do not use exposed hot bulbs.
  • Remind students not to stare directly into the lamp.
  • Mark an observer viewpoint.
  • Keep the model focused on illumination and geometry, not scale.
  • Open Teach Mode.

Prior knowledge

  • The Sun is a source of light.
  • The Moon can be seen in different apparent shapes across time.

Vocabulary

phase
The appearance of the Moon's sunlit portion as seen from Earth.
orbit
The curved path one object follows around another.
illuminated
Lit by a source of light.
crescent
A phase when less than half of the Moon's visible disk is illuminated.
gibbous
A phase when more than half but not all of the Moon's visible disk is illuminated.
viewpoint
The position from which an observer sees an object.

Differentiation

  • Use pre-drawn circles for students to shade.
  • Let students rotate a model in pairs before writing.
  • Use the frame: The side facing the Sun is ___. From Earth we can see ___.
  • For extension, ask students to compare waxing and waning positions without requiring memorization of all eight named phases.

Assessment

  • Check whether the lit half always faces the lamp.
  • Check phase sketches from the Earth viewpoint.
  • Check correction of the Earth-shadow misconception.
  • Check identification of model limitations.

Exit ticket

Explain why the Moon can appear crescent-shaped even though half of the Moon is illuminated by the Sun.

Extension

Track the Moon's appearance on several clear evenings using drawings or verified images, then compare the observed pattern with the classroom model.