Our research addresses the issue of teaching and learning concepts in science education as an empirical question. We study the process of conceptualization by closely examining the unfolding of classroom lesson sequences. We situate our work within the practice turn line of research on epistemic practices in science education. We also adopt a practice turn approach when it comes to the learning of concepts, as we consider conceptualization as being inherent within epistemic practices. In our work, pedagogical practices are modeled as "learning games" and epistemic practices in science education are characterized as "enacted epistemic games" emerging through the unfolding of learning games. Science practices are modeled as "source epistemic games" since they are the source of the knowledge at stake in pedagogical practices. From this point, we examine closely how playing learning games can enable students to play enacted epistemic games and then in turn the source epistemic games at the core of conceptual understanding. Thus, the main contribution of this paper is to link pedagogical practices to epistemic practices in science education and to science practices in general. Our method is consistent with this epistemological framework as our case study on the concept of earthquakes in a 5th grade classroom sequence illustrates. Following an investigation of two experienced teachers and their classes during a teaching unit, our analysis shows how teaching effectiveness is determined by a dialectic. This entails on the one hand a didactic continuity between learning games and enacted epistemic games and, on the other, an epistemic continuity between enacted epistemic games and source epistemic games.