Reflection on teaching in higher education remains poorly understood. This exploratory study had three goals. First, to test, empirically yet in an exploratory way, the applicability of a particular model of reflection. Second, to identify objective indicators of reflection on knowledge about teaching with the intent to make the process of reflection more concrete, visible, and its outcomes valid. Third, in line with the exploratory nature of the study, to shed light on some variables that might be linked to observed differences in reflection, which could be investigated more systematically through future research. The model of reflection guiding the study was based on Mezirow's transformative learning theory. It distinguishes three kinds of reflection: on content, process and premises. These take place within three domains of knowledge about teaching: instruction, pedagogy, and curriculum. Thirty-six instructors of science participated in a semi-structured interview based on the model and completed a repertory grid, which incorporated their beliefs about teaching as identified through the Approaches of Teaching Inventory (ATI). While all instructors showed evidence of reflection that were in line with the model, differences were observed in the extent or kind of reflection they engaged in. Across all three knowledge domains, premise reflection was observed the least often. Results suggested that years of experience and beliefs about teaching might play a role in the extent to which academics are inclined to engage in reflection. The study also identified concrete indicators of reflection, which could be helpful for academic staff evaluation.