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Lesson plan · Grades 6-8 · 45 minutes

Moon Phase Model

I can use a model of the Sun, Earth and Moon to explain why the Moon has phases and why we don't get an eclipse every month.

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Standard
MS-ESS1-1 NGSS
Shape
Explore first
Grouping
Pairs on devices, then small groups with the lamp.
You need
The tool on the projector and on student devices. A lamp with no shade and a ball on a stick (or a foam ball on a pencil) for Apply.
Tool
curioclass.org/tools/moon-phase-model/
  1. Hook5 min
  2. Explore15 min
  3. Make sense10 min
  4. Apply10 min
  5. Exit check5 min

Before class

  • Open Explore. The left view is space, with sunlight from the right. The right view is a backyard facing south.
  • Set up the lamp in a corner you can darken, for the ball-and-lamp model.
  • Note that the model isn't to scale. The real Moon is about 30 Earth widths away.

Hook 5 min

  1. "Is the Moon ever really a half circle? Does part of it disappear?" Take a quick vote.
  2. "A common answer is that Earth's shadow causes the phases. Today you test that idea with a model."

Explore 15 min

  1. Pairs press each phase button, or drag the Moon around its orbit. For each phase they record: which half of the Moon is lit, and which half faces Earth?
  2. Pairs drag the green You dot around Earth to change the time. Everything above the dashed horizon line is in your sky. "When is the full moon up? When is the first quarter moon highest?"
  3. Pairs play days at 9 pm and watch the Moon's shape and place change night after night.
  4. Pairs switch to Predict. The backyard shows a Moon at some time of day; they drag the Moon in space to match and press Check my Moon.

Make sense 10 min

  1. Back to the vote. "Is it Earth's shadow?" (No. The Sun always lights half the Moon, and the phase is how much of that lit half we see.)
  2. "Why can't we see a new moon, even though it's in the sky all day?" (The lit half faces away from us, and the Moon is next to the Sun in the sky.)
  3. "A full moon is opposite the Sun. Why don't we get a lunar eclipse every month?" Turn on Tilt and eclipses to check. (The Moon's orbit is tilted about 5°, so usually it passes above or below Earth's shadow.)

Apply 10 min

  1. Groups use the lamp (the Sun) and the ball (the Moon). One student is Earth and holds the ball at arm's length, turning slowly in a circle.
  2. Find the new, first quarter, full and third quarter moons. Each group sketches the four in order.
  3. "Hold the ball where a lunar eclipse could happen. Why only sometimes?" (The ball must line up exactly in your head's shadow.)

Exit check 5 min

On a card, draw the Sun, Earth and Moon for a first quarter moon. Label the lit half of the Moon and the half we see from Earth. Then write one sentence on why phases aren't caused by Earth's shadow. Drawings with the Moon in Earth's shadow show who needs the model again.

Support and stretch

  • Support: work with only four phases: new, first quarter, full and third quarter.
  • Support: keep the space view and the backyard side by side, and point at the same Moon in both.
  • Stretch: "The Moon rises about 50 minutes later each day. Use the model to explain why."
  • Stretch: "In the Southern Hemisphere the lit side is flipped. Why?"

Short on time

  • Phase buttons in Explore, with the lit half and the facing half (10 min).
  • Tilt and eclipses as a class (5 min), then the exit drawing (5 min).

How each button works is in the teacher notes. From Curio Class, free under CC BY 4.0: change it, print it, share it.