Maps often present geographical boundaries through linear symbols. If teaching directly equates the symbolic form with the objective boundary, it is likely to place emphasis on memorizing boundary locations and the characteristics on both sides, while paying less attention to the analysis of boundary-delineation criteria, transition ranges, scale changes, and cross-boundary connections. Based on natural regionalization, scale thinking, and research on boundaries, this article analyzes the relationships among geographical dividing lines, transition zones, and geographical boundaries. It categorizes boundary representations in senior high school geography as abrupt boundary lines, threshold boundary lines, and transitional boundaries, and summarizes their criteria dependence, scale dependence, dynamic mobility, and the duality of regional division and connection. On this basis, it constructs a geographical-boundary cognition process of“boundary delineation, identification, interpretation, and application”and proposes teaching pathways including multi-indicator overlay, map zooming and profi le transformation, temporal map overlay, and multi-boundary overlay. These pathways promote the shift in boundary learning from memorizing dividing lines to understanding the generative logic, spatial forms, formation processes, and conditions of application of boundaries.