This study explored young children’s under- standings of targeted lunar concepts, including when the moon can be observed, observable lunar phase shapes, predictable lunar patterns, and the cause of lunar phases. Twenty-one children (ages 7–9 years) from a multi-aged, self-contained classroom participated in this study. The instructional intervention included lunar data gathering, recording, and sharing, which integrated Starry Night planetarium software and an inquiry-based instruction on moon phases. Data were gathered using semi-structured interviews, student drawings, and a card sorting activity before and after instruction. Students’ lunar calendars and written responses, participant observer field notes, and videotaped class sessions also provided data throughout the study. Data were analyzed using constant comparative analysis. Nonparametric statistical analyses were also performed to support the qualitative findings. Results reflected a positive change in children’s conceptual understanding of all targeted concepts including the cause of moon phases, which is remarkable considering the complexity and abstractness of this spatial task. Results provided evidence that computer simulations may reduce the burden on children’s cognitive capacity and facilitate their learning of complex scientific concepts that would not be possible to learn on their own.