Moon Phase Box Model

Introduction: Moon boxes provide one way to model the phenomena of moon phases. Used in conjunction with other solar system models they can help build an understanding of the geometry of moon phases, providing a self-contained, and visually memorable, project. This activity suggests a mathematically and visually interesting extension: experimenting with differently shaped moons.

Background:

As the moon orbits around the earth (in just over 27 days), we see different moon phases going from the new moon, slowly increasing towards the full moon (waxing), then slowly decreasing (waning) back to a new moon. Of course, the moon itself does not change shape — and the sun always illuminates exactly half of the moon, just as it always illuminates half of the earth. The moon phases change because of the relative positions of the earth, moon, and sun. At full moon we see the full illuminated half of the moon; at other phases, we see only a part of the illuminated section of the moon. (Sometimes we can faintly see the unilluminated section as well — a phenomenon known as earthshine.) All of this is nearly impossible to explain in words, so making models is very useful in learning about these phenomena.

Since no model can accurately show all of the relationships of the solar system, it is best to use several different models and discuss the strengths and weaknesses of each. The moon box model does a good job of showing the visual phenomena, but it does not show how the different viewing angles relate to the orbit of the moon around the earth. Ideally, before using the moon boxes I would use a full-body model, with a lamp in the center of a darkened room for the sun, a student as the earth, and the moon as a ball that can be “orbited” around the earth (see resources below). This gives a good sense of why our viewing angle changes. The moon box can then provide a way to experiment further. Also, see the resources section for moon observation ideas.

You can use the "Moon Phase Sheet" to have students try to draw the moon phases before investigating any of these models, or making moon observations, and then have them return to their predictions and redraw the phases after building the models and observing the moon.

Cardboard Box ( at least 8” x 11” x 4” )

Construction Paper (dark blue or black)

Clay or Styrofoam ball (about 1.5” in diameter)

Stiff wire (about 6" -- a large bent paper clip is fine)

Small Flashlight

Tape, Scissors, Pumpkin Carving knife, and dark blue paint if available

There are many directions for moon phase boxes available on the web (see resources section below). The exact dimensions of the box do not matter, something at least 8” x 11” x 4” works well.

Students will need to cut holes in the box. There is some interesting math and measurement involved in where to place the holes. Students can measure the centerline (top to bottom), and figure out the placement of the view holes along this line. You will need one centered hole on a short side of the box for the flashlight. Then another view hole right next to it for the view of the full moon.

On the opposite short side, one centered hole will give a view of the new moon. If you make three holes on each long side of the box, you can observe the whole cycle of waxing and waning. On the long sides of the box, any position along the centerline is “valid” but start with a hole in the center (the quarter moon), and then divide the remaining spaces in half to view the crescent and gibbous moons.

Once the hole positions are marked, use scissors to punch a hole. Then cut a view hole with scissors or use a pumpkin carving knife. If this is challenging for your students you can have them cut slots up from the bottom of the box, eliminating the need to stab into the box with scissors.

You will need a small ball for the moon, and wire or another way of hanging the moon in the center of the box. You can use a Styrofoam ball for the moon, but I find a small clay ball (ideally gray or some light color) is less reflective and works better. (Clay is also necessary for the extension activity.) The ball should be about 1.5” in diameter, and at least as big as the lens of the flashlight so that the moon will easily cover the view of the flashlight in the “new moon” view.

You can paint or cover the inside of the box with dark construction paper. Making paper flaps to cover the holes helps keep out excess light and improves the effect.

When you turn on the flashlight, you should see the different phases of the moon as you look into the different holes (make sure the moon is hanging in the direct path of the flashlight). Have students return to their datasheet and carefully draw the moon phases as they see them in their box.

What would happen if the moon was not round? Have students think about a cool new shape for our moon, then take out the clay moon and make the ball into the new shape. Before they test their moon in the box have students predict how it will look at the different phases and use the datasheet to draw their predictions. Then test the fantasy moon in the box and draw the results.

This extension involves spatial thinking, some interesting geometry, and can be quite tricky depending on the shapes students invent!

The resources section gives ideas for additional models, and how to engage students in real-life moon viewing.

Detailed directions for a moon phase box (one of many on the web):

https://www.instructables.com/Educational-Phases-o...

Whole-body model of sun, earth, and moon (one of many):

Models to show the relative size of the earth and moon, and the moon’s influence on tides: https://www.exploratorium.edu/snacks/earth-moon

Moon viewing ideas:

https://mass.pbslearningmedia.org/resource/ess05.sci.ess.eiu.lp_lunarcycle/the-lunar-cycle/

https://www.youtube.com/watch?v=rFXsXAPVl3Q

This work is made possible by support from STAR, a Biogen Foundation Initiative. The team at Lesley supporting this initiative includes faculty and staff in the Lesley STEAM Learning Lab, Science in Education, the Center for Mathematics Achievement, and other related Lesley University departments and programs.