M.Ed. / This qualitative study, with an ethnographic research design type, was mainly aimed at determining how Life Sciences teachers implement a learner-centred and activity-based investigation (science as enquiry approach) in reaching the learning outcomes in the Life Sciences curriculum and also how they function within their respective communities of practice (in the school) and ecologies of practice (within the clusters) with a view to promote continuous professional development. Because teaching and learning are in essence a social activity, the Cultural Historical Activity Theory was used as the theoretical framework and lens in studying the activity system of the Life Sciences teacher. The levels of Pedagogical Content Knowledge (PCK) of individual respondents were classified according to Rogan‟s Profile of Implementation for Science teaching. The recommended teacher development programme is based on Vygotsky‟s Zone of Proximal Development and Rogan‟s Zone of Feasible Innovation. The study was undertaken during the same period in our country as that in which education in general and science teaching in particular is confronted with huge demands/dilemmas. Amongst others, it includes a poor performance of matriculants and the fact that South African learners have performed poorest in international tests (TIMSS report). The data of this study, collected by means of observations, teacher and learner interviews and studying documents, unfortunately confirm this sombre picture, namely that many teachers do not possess the minimum Pedagogical Content Knowledge (PCK) (inter alia deficient subject knowledge and inability to apply effective teaching methods) to make possible, quality teaching with regard to the facilitation of investigating teaching methods. A further finding also was that although the elements of a community of practice and ecology of practice exist, it is, in most cases, not used as a platform from which teachers empower one another with respect to teaching skills.