Assessing student learning during simulations in education: Methodological opportunities and challenges when applying a longitudinal case study design

•A longitudinal case study design can be an efficacious research strategy for assessing simulation-based learning.•Such a design is illustrated through a previously conducted study in the context of political decision-making.•‘Triangulation’ and ‘chain of evidence’ are of utmost importance to ensure reliability and validity.•Opportunities and challenges for a longitudinal case study design are discussed in seven lessons learned. Simulations are complex learning environments, especially when they are designed such that student agency intensively shapes the simulation process. Investigating student learning during the simulation process requires a methodological approach that is able to take contextual influences and fluctuations of processes into account and produce rich, exhaustive descriptions of how student learning unfolds during a simulation. In this paper, we present a methodological approach to assessing student learning in simulations and reflect upon the lessons learned from this approach. We detail a longitudinal case study design in the context of a role-play simulation of political decision-making and critically examine the research opportunities and challenges it presents by focusing on the alignment of theory and research goals, aspects of context, sampling, measurements and procedures, and the role of the researcher.