This study concerns the use of mathematical talk in the teaching of mathematics. It looks at two teachers' pedagogical issues and how one of them translates ideas of classroom discussion into practice in mathematics lessons. Literature on group work which I had learned in the course of my M. Ed programme claimed that mathematical discussion enhances pupils' understanding of mathematics. So I planned to study these claims through the work of other teachers, Ms Husan and Mr. Rahim. The research study also considers aspects of mentoring experienced teachers and the resulting implications, and explores tensions and concerns which are a consequence of mentoring relationships. The research uses, extensively, classroom observation methods to investigate what happens as a teacher attempts to put into practice those ideas which were earlier negotiated in mentoring sessions. Data were collected by means of classroom observations (written notes about my perceptions of lessons), interviews with teachers and from teachers' diaries - written comments about lessons. Another source of data was my own personal reflections about what I saw and heard teachers doing and saying about their work. These personal accounts of what occurred, which I recorded in my reflective journal, constituted my perceptions of events. Mr. Rahim showed no interest in discussion-based methods of teaching. Although it might have been educationally sound for him to introduce changes in his pedagogy, he did not see classroom innovations as one of his immediate needs. Possibly he did not understand the objective of using group work as an instructional strategy. He was concerned about the impact of this strategy on his students. His biggest concern was time and completion of the syllabus. He lacked personal philosophy in the process of professional growth. He cited time constraints and school exams (end of year) as the major obstacles to implementing new ways of teaching. He, therefore, preferred to conserve his expository methods because they enabled him to cover a vast amount of the curriculum within short periods of time. Perhaps he took pupils' understanding of the subject matter for granted.