Phases of the moon: Exploring perceptions from around the globe and outer space

Tuesday 3:40pm-4:00pm Weeks Geo: 140
Teaching Demo


Scott Clark, University of Wisconsin-Eau Claire


I will demonstrate how this activity is set up and implemented.


Cream-filled, chocolate sandwich cookies, such as Oreo®, are a popular way to teach students about the phases of the moon, and numerous images and lesson plans are readily available online. However, activities that show an internally consistent model and that challenge students to grasp the underlying cause of the moon's phases are not. The activity that I will be presenting uses sandwich cookies in a novel way that is designed to challenge alternative conceptions and to provide students with a conceptual understanding of the Earth-Sun-moon relationships. Students use two sandwich cookies for each phase, with one cookie modeling how the sun is always illuminating half of the moon, and the other showing the appropriate phase of the moon as observed from Earth. The cookie activity is supplemented with a second activity that requires students to manipulate a half-painted plastic golf ball that represents the moon and a slightly larger ball that represents Earth. Beyond furthering the students' abilities to identify the moon's phase based on the Earth-Sun-moon positions, manipulation of these objects helps the students to visualize why the mnemonic device "last light left" for a waning crescent moon is only applicable in the northern hemisphere.


This activity is used in an Earth Science course which is specifically designed to meet the needs of Elementary Education and Special Education majors.

Why It Works

The innovative aspect of this version of the sandwich cookie activity is that two sandwich cookies are used for every phase, with one cookie modeling how the sun is always illuminating one-half of the moon, and the other cookie modeling the phase of the moon as observed from Earth. The use of an Earth ball and a golf-ball moon are effective in showing how the appearance of the moon's phase changes based on the observer's latitude.