The mandate of the new South African curriculum for educators to enact a science-indigenous knowledge curriculum in their classrooms is not only challenging to their cosmological beliefs, it is equally challenging to their instructional practices. This is because science educators (teachers) in South Africa have been schooled largely in western science and lack the necessary knowledge or skills on how to achieve such a goal. In response to these challenges nine experienced educators were exposed to an activity-based Dialogical Argumentation Instruction (DAI) for a period of 12 months. The DAI served as an exemplary instructional model for the educators to use in their classrooms. A questionnaire and an interview were then used to determine the effects of DAI on the educators' cosmological beliefs about certain natural phenomena. Although DAI seemed to have influenced the educators' worldviews in a variety of ways, their overall cosmology remained essentially amalgamated with their religious beliefs dominating. The implications of the findings for instructional practice are highlighted in the article. (Contains 2 tables.)