The new South African curriculum known as Curriculum 2005 (to depict the year of its full implementation) requires that teachers integrate school science with Indigenous Knowledge Systems (IKS). Curriculum 2005 has generated heated debates at various levels since its inception in 1997. This study focuses on the effectiveness or otherwise of a Practical Argumentation Course (PAC) as an instructional tool for enhancing teachers' understanding of, and ability to implement, a Science-IKS curriculum. Data collected by questionnaires, video-taped and audio-taped interviews, and reflective essays were analysed in terms of a Practical Argumentation Framework developed for the purpose. The findings show that the PAC did enhance the teachers' understanding as well as increase their awareness of the need to implement a Science-IKS curriculum in their classrooms. Also, the PAC seemed to have made the teachers more skeptical of the notion that science is the only way of knowing or interpreting experience, or that IKS were based on superstitious beliefs. All the teachers recommended the need to include the PAC or similar courses in science teacher education programmes.