This paper focuses on an analysis of an application of active learning in the international relations (IR) classroom. We present an experience of the so-called Challenge Game that allows the professor to explore analytical categories and basic assumptions of realist theory of IR. In addition, describing the operation of the game in its basic modality, several variations are also presented in order to help explore realism, both in its classic and structural version. We show that key concepts found in realist and neorealist theories, such as the elements that influence the behavior of states in the international system, different conceptions of power and interests, aspects of competition, the centrality of the rationality of the state, alliances building, balance of power, the anarchy of the system, and the idea of hegemony can be either introduced or revised in a dynamic fashion in an IR theory class. The game has been thought to provide means to promote active (instead of passive) learning. As a result, the class can become more dynamic, with the consequent increase of the students interest on the issue. Besides, the activity can provide an environment for discussion, boosting students' potential to think about the content.