Chemists refer to chemical phenomena on different representational levels--macroscopic, symbolic, and submicroscopic--which are directly related and connected to each other. Especially in the laboratory, students have to reason about various mechanistic features at the submicroscopic level and connect them in a meaningful way to make sense of the observable. There is plenty of evidence in chemistry education that students have difficulty connecting the different representational levels when thinking about chemical phenomena. However, current literature provides limited information about the mechanistic features that students activate when reasoning about phenomena and how they transition between the representational levels when in an organic chemistry laboratory. In this study, we performed in-depth analysis of how organic chemistry student teachers (N = 9) explained typical work-up procedures and characterized their activated mechanistic features and transitions between the different representational levels. Our analysis revealed that the students do not activate all features of a mechanism in the same way and construct various explanatory approaches. The findings emphasize the need to explicitly communicate how to connect the macroscopic and submicroscopic levels in a meaningful way in the laboratory. The implications of these findings for research, teaching, and learning to foster meaningful activation of mechanistic features are discussed.