This study documented the means by which STEM (science, technology, engineering, and mathematics) educators experienced the mathematics and science associated with understanding lunar phenomena. The article reports how well STEM education graduate students interacted with projectbased materials as they engaged in interdisciplinary teaching and learning. Research questions pursued were: (a) How will students' spatial mathematics and scientific understandings develop as they engage in a contextualized, technology-rich, project-based environment? and (b) How will the students' group projects affect their understanding of lunar related concepts? A mixedmethods approach was used with this semester-long design study to expose how focused project work facilitated spatial understanding. Significant gains were made on lunar-related concepts that had been previously resistant to conceptual change (lunar motion and effect of lunar phase with location change). An implication of this study suggests that technologies (i.e., Stellarium, online blogging with Australia, and Geometer's Sketchpad) facilitated students' project progress, aided students' understanding of how perspective matters in terms of Earthly sky viewing, and deepened students' understanding on domains that included spatial reasoning.