Effects of a discursive course on two science teachers' perceptions of the nature of science

South Africa's Curriculum 2005 (C2005) for the natural sciences stresses that learners develop a valid understanding of the Nature of Science (NOS). This presupposes that teachers possess a valid understanding of the NOS. This paper describes a case study which explored the relative effects of a semester-long NOS Course (NOSC) on two science teachers' perceptions of the NOS. The course used a discursive approach, centred on argumentation and drawing not only from the History and Philosophy, but also from the Sociology of Science. The findings show that based on their experiences in the course, the teachers were more inclined to present science not as an immutable body of knowledge but as a dynamic, tentative, dubitable, revisionary and a multifaceted human enterprise. Likewise, the teachers were more sceptical of scientism and more aware not only of the psychosocial contexts of scientific practices but also the controversies, fierce competition and sometimes vitriolic wrangling that arise among members of the scientific community. The study points to the value for teachers of approaches that bring together historical, philosophical and sociological perspectives of the nature of science, and centre on processes of argumentation.