Finally, the students of each class who delivered the group’s oral presentation were interviewed separately in two focus groups to elicit deeper reflections on the activity, based on the questions listed in the questionnaire. All interviews were videotaped. The interviews were followed by a debriefing session conducted by both the teacher and myself to discuss what we had observed and to address some of the learning issues identified during the activity. The transcribed data were analysed to identify emergent themes of student reasoning at two levels. The first level, targets of analogy, depicted the specific aspects of cellular respiration regarding which the students drew analogies. The second level, analogy, was the analogue–target relationship drawn by students with respect to individual targets. In analysing these data, particular attention was paid to the following questions related to the key concepts of cellular respiration.