This paper aims at examining the use of a theoretical and methodological framework originating in ergonomics, the 'course-of-action method', in the study of individual learning processes in naturally occurring situations. This framework investigates the course of lived experience of each individual. Thus, in addition, to her/his thinking, it affords to analyse her/his concerns, her/his perceptions, her/his feelings and the activity that s/he attributes to her/himself. The method involves gathering two types of data about a short time-stretch: video-data and 'self-confrontation interviews'. During such an interview, one views a video of oneself and reporting what one experiences at every instant. These data are analysed by identifying and characterizing successive units for describing individual experience, and by comparing these descriptions synchronically and diachronically. The method has been used for fined-grained studies of lived experience of learners in various contexts. In this paper, its implementation is exemplified by a case study about understanding in a teacher training context. We discuss the extent to which it allows overcoming some limitations of both socio-cultural approaches in learning research and microgenetic studies of conceptual change.