Concept maps make students' knowledge visible. Creating a mind map gives students an opportunity to organize their knowledge and allows instructors to visualize and assess it. When students create mind maps at multiple time points, instructors can compare the maps and use the themes, patterns, and gaps that emerge to reflect on their teaching and take action. The purpose of this study was to use concept maps in an AAC course to uncover students' knowledge. A total of 61 graduate students created a mind map with AAC as the central concept at the beginning and end of the term in a graduate-level AAC course. The researchers calculated frequency counts of concepts and connections on each map and completed categorical analyses. Analysis revealed an increase in students' breadth and depth of knowledge of AAC and related concepts. Concepts related to populations of AAC users, access methods, collaboration, and high tech and no tech AAC systems appeared most frequently on participants' mind maps. Assessment, intervention, and funding concepts appeared less frequently. Benefits and challenges to implementing concept maps are discussed so educators can consider how concept mapping may be useful in their contexts.