Understanding probabilities and methods for calculating them is crucial as students progress to advanced topics in probability theory in upper secondary education. The game “Borel” (Anagnostopoulos & Doxiadis, 2017) serves as an engaging way to explore students’ existing ideas about probability (Allmendinger et al., 2021). The combination of chance and strategy in the game not only makes learning about probabilities entertaining but also stimulates in-depth debates over seemingly simple random experiments. The game can be used in a variety of ways in the classroom (Aslaksen et al., 2025) and students can be playfully introduced to typical random experiments. Playing the game encourages the use of probabilistic thinking as a strategy, enhancing students' argumentation skills and clarifying their understanding of probability. Devising optimal betting strategies with the students offers great diagnostic potential (Allmendinger et al., 2021). In our research, we sought to explore the utility of the game to enhance probabilistic thinking in mathematics classrooms. While probabilistic thinking has been extensively studied, the role of argumentation and reasoning as a central component of learning in this context has received limited attention. Students often struggle to understand what constitutes a valid argument and how to construct one. By providing opportunities for argumentation through engaging activities like Borel, we aim to address this gap.