Look for: Describing each lunar phase

Develop and use a model of the Earth-Sun-Moon system to explain and predict patterns we observe in the way the apparent shape of the Moon changes over time.

Check to make sure students are including these details:

• Describing each lunar phase.
• Adding the Moon on the circle that represents its orbit in the position related to each phase.
• Do not expect students to be exact about waxing or waning phases.
• Accept crescent and gibbous Moons at the top left/right of the orbit or at the bottom left/right of the orbit.
• Distinguishing the lit and unlit sides of the Moon.

• If students are not accurately distinguishing the lit and unlit sides of the Moon, encourage them to return to the physical model and make observations of the sunlight on the Moon.
• If the placement of the Moon is inaccurate, have students draw lines from the observer to the sides of the Moon facing Earth to more concretely frame how much of the lit part of the Moon the observer could see.

Create a class version of the Moon phases chart. Display slide N. Bring the class back together and ask students to volunteer to share their understanding of each phase. As students share, record at the front of the room a version of the diagram from Shape Patterns of Earth-Sun-Moon System on a sheet of chart paper labeled “The Phases of the Moon.” Again, point out the perspective of looking down on the North Pole of Earth. Add the position of the Moon in the system for each phase as students share. Add two Moons for the crescent and gibbous Moons.

Ask students how to show the unlit side of the Moon in Shape Patterns of Earth-Sun-Moon System and decide how you will represent this as a class. The convention used throughout this unit is a striped region, but each class may choose something different. Keep track of the choice in a key on the diagram you are making, and reassure students that it is OK if they used a different representation for the unlit side of the Moon; the important thing is that they represented it in some way.