Ideas for teaching the phases of the moon

by Stephanie Chasteen on April 27, 2010

A while back, a teacher on a listserv asked for some ideas and resources for teaching the science of the phases of the moon.  Veteran teacher Eric Plett shared this great hands-on activity that I thought merited a blog post of its own.

1.  Darken your room and get a bright light source like an overhead projector.  Turn it on and project it toward your students.

2.  Give each student a tennis ball (or a white Styrofoam ball that you can buy at Michael’s is even better).  Have them hold the ball out away from their face and slightly above their heads (so that they don’t immediately experience a ‘lunar eclipse’).

3.  They can start with the ball opposite the light source – full moon phase.  Then while maintaining the ball position they turn their bodies to see the phases of the moon.  Have them turn in unison and you can call out the phases that they will see.  They can experience a solar and lunar eclipse when the ball obstructs their line of sight to the light and when their heads block the light hitting the ball.

Says Eric: “It was a great ‘real’ experience for my students and they not only knew the phases but the why behind them.  It is usually an epiphany for them.”

Another activity on the moon is on one of my Science Teaching Tips podcast, from the Exploratorium, about the relative size of the full moon:

When the Moon Hits Your Eye.  What coin would just barely cover the full moon? You may be surprised. TI director (and recovering astrophysicist) Linda Shore explains how our brains distort the actual size of the moon.     Download mp3


Since I posted this, I got several comments on my Facebook page from readers:

David Colarusso says:  I used to do this with my astronomy students, but might I recommend tangerines over tenis balls. It helps with the digestion of a new concept if you can actually digest the subject of your study. 😉

Paul Doherty says:  Hi Steph,  I go out during the day when the moon is in the sky with a white ball. I hold it up in the sunlight right next to the moon in the sky….it has the same phase as the moon.  🙂 for the same reason.

Helen Fields says:  “We did this in my earth science class (with a white styrofoam ball, ’cause you can put a pencil into it and hold it that way) in about 1994 and it was great – I still remember the phases of the moon that way. “


AmoebaMike April 27, 2010 at 11:29 pm

I’m afraid I can’t visualize this very well. I might have to try a way to test this out at home. 😀

John Weiss May 2, 2010 at 8:56 pm

I do this activity every time I teach Intro. Astro. I use the foam balls and I get some sticks and impale them. It makes it a bit easier for the students to manipulate them. (It also helps if you can paint the moon-balls because the styrofoam scatters the light internally somewhat, muting the overall effect slightly. I’ve never bothered myself, but the amazing observatory manager at CU, Keith Gleason, did so for their set and it was a sweet, sweet setup.)

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