The purpose of this study was to try to understand how practising teachers learn new teaching practices with the help of a mentor. The study documents the cases of two secondary school teachers learning to promote talk in the mathematics classroom. The author of the study played the dual role of a researcher and mentor to these teachers. The field work lasted for seven weeks during which the mentor and mentees worked in close collaboration. They planned talk promoting activities and lessons, carried them out in class and reflected on their own and pupils' learning in the process. The research draws on qualitative data from sources such as semi-structured interviews, participant observation and teachers' reflective journals. What the researcher learned is that change is a complex phenomenon. The process of change is influenced by the teachers' beliefs , ideas and understanding pertaining to the various aspects of the innovation and personal readiness for change. Contextual factors such as time, prescribed syllabi and examination as well as the teachers' relationship with the mentor were seen to influence the way teachers learned. Although the study is based on the analysis of only two cases, it provides some insights into the process of change when teachers become learners.