Abstract: The ability to make spatial judgments and visualize has been shown to be a strong indicator of students’ future achievement in STEM-related courses. Spatial intelligence has also been shown to be one of the only areas in which females perform worse than males, with noticeable differences emerging in the middle school years. However, research has also shown that very short duration training exercises can close the spatial reasoning gender gap. Therefore, the goal of this investigation was to assess the design a functional prototype of a Minecraft-based spatial skills intervention for middle grade (4th – 7th grade) students. Participants (n = 32) engaged in a series of two-day Minecraft camps focused on mental rotation and 2D-to-3D transformation. Pre- and post-tests were administered to better understand the possible influence of the activities on learners’ spatial skills. Despite the small sample size, findings suggest that learners did increase their mental rotation skills, but with no growth found in 2d-to-3d transformation skills. Results from this study will be used to adjust the activities and inform the design of new Minecraft-based activities focused on other specific spatial skills. Moreover, this study can provide insight into how gaming systems can be used teach skills critical to achievement in STEM, address gender differences in spatial skills, and ultimately strengthen and diversify the STEM workforce.