Thoughts about reflection and reflective practice have evolved over many decades, through carefully constructed theory and research applications, mainly based on the work of Dewey (1933) and Schön (1983). Evidence also exists in the literature that the ability to reflect on practice is considered a necessity for effective instruction (Sowder, 2007). By reflecting critically teachers become more positive in the search for a new understanding of their teaching practice and design more ways to deal with the challenges that confront them daily. When teachers act reflectively, they consider carefully the problems in their own teaching and think about how those problems are related to their educational or social context. They are aware of the consequences of their teaching and how their own assumptions or beliefs can influence their teaching. This main purpose of my research study was to explore the nature of mathematics teachers’ reflective practice in the context of lesson study. To achieve this aim, an in-depth exploration of five mathematics teachers’ reflection before, during and after teaching a lesson was conducted. The possible relationship between these teachers’ reflection and their classroom practice was also examined. The research also aimed to explore whether and how mathematics teachers’ reflections differ from the conceptualisations of reflection in classroom practice as found in the literature. Contextual factors that might influence the nature of mathematics teachers’ reflective practice were also investigated. My findings indicate that the mathematics teachers in my sample have a limited understanding of the concept of reflection. Furthermore, based on lesson plan analysis, there was no evidence that these teachers reflect-for-action. However, they all reflected on-action verbally and in writing, and three of the five teachers reflected-in-action while teaching. They all reflected on Level R1 (recall level of reflection) and Level R2 (rationalisation level of reflection) and three teachers reflected critically on their learners’ understanding of mathematics and their own teaching of concepts towards the end of the research project (Lee, 2005). Language and the lesson study group experience emerged as contextual factors that seemed to influence the teachers’ reflection. Although the research study’s results cannot be generalised due to the small sample, I believe that through engaging in the lesson study experience the five teachers of this study improved their reflective practice, reporting an increase in self-knowledge and finding new ways of teaching mathematics to learners. / Thesis (PhD)--University of Pretoria, 2011. / Science, Mathematics and Technology Education / unrestricted