In this paper, we examine the conceptual understanding and experiences that students in German secondary schools have of boundaries. For our research we conducted qualitative interviews and surveys (interviews n=20; surveys n=21) with children (aged 14-17) born both in Germany and with refugee backgrounds. We asked for the children's conceptual understanding of the emergence and function of boundaries and their personal encounters with them. We studied the results of these interviews using qualitative content analysis to learn more about the conceptual understanding and experiences of students. Our findings on the emergence of borders show that students have limited understanding of boundaries and differing spatial concepts that exist for them. We also observed interesting distinctions between personal experiences of borders. The results may provide a base for further research and development in terms of conceptual-change-based methods for geography education on the topics of territories, borders and boundaries.