Nearly 20 years after the release of The Harvard-Smithsonian Center for Astrophysics' video, "A Private Universe", much research has been done in relation to students' understanding of space-science concepts and how to effectively change these ideas. However, student difficulties with basic space-science concepts still persist. This article will…

Presents research on different techniques to determine the level of understanding among middle school students regarding the phases of the moon. Quotes student responses to provide some insight into students' level of understanding of general knowledge about the moon, moon phases, and modeling the phases. Presents implications for teachers. (KHR)