A CD-ROM consisting of videos of two lessons by different teachers demonstrating exemplary science teaching was used to elicit, develop and track the changing conceptions of good science teaching of student teachers enrolled for the one-year Postgraduate Diploma in Education (PGDE) at several stages during the programme. It was found that the videos acted as an effective probe to elicit student teachers' conceptions and had significant impact on those conceptions at different stages of the programme through the provision of teacher models demonstrating exemplary teaching. The experience has extended novice teachers' awareness of alternative teaching methods and approaches not experienced in their own schooling, broadened their awareness of different classroom situations, provided proof of existence of good practices and prompted them to reflect on their current conceptions of good science teaching. Most importantly, the strategy of asking student teachers to watch the same videos on three separate occasions at different times of the course was recognized by them as a crucial element in facilitating their reflection on their changing conceptions of good science teaching.