The Moon is an ever-present subject of observation, and it is a recurring topic in the science curriculum from kindergarten's basic observations through graduate courses' mathematical analyses of its orbit. How do students come to comprehend Earth's nearest neighbor? What is needed for them to understand the lunar phases and other phenomena and concepts in astronomy? This article describes an activity in which middle school students learn about the phases of the Moon and using different frames of reference. The premise behind this activity is that if students develop an understanding of the relative positions of the Sun, Earth, and Moon, then they can reason their way through an explanation of the phases. To accomplish this, students must also develop an ability to change their frames of reference. By role-playing the positions of Sun, Earth, and Moon relative to one another, this kinesthetic activity addresses student misconceptions related to the cause of the lunar phases, teaches students the correct reason for the changes in the Moon's appearance, and helps them develop their abilities to use various frames of reference. (Contains 1 figure.)