ABSTRACT
Thinking about subject-knowledge expertise for science teachers, and consequently how ITE programmes tackle it, has been influenced considerably by Shulman and his associates (Shulman 1986, 1987; Shulman and Grossman 1988). In the 1980s they argued that in order to make the subject accessible to pupils, teachers needed a new knowledge base besides subject-matter knowledge and pedagogical knowledge. That base arose from the merging of the two to form pedagogical content knowledge (PCK) which comprised knowing what, when, why and how to teach using a reservoir of knowledge of good teaching practice and experience. In cultural-historical terms, PCK therefore operates as a secondary artefact (Wartofsky 1973). Cole (1996) explains that primary artefacts are those tools such as axes which are actually used in production; secondary artefacts are representations of primary artefacts and include recipes, beliefs and norms which preserve and transmit current ways of acting and thinking; tertiary artefacts, while still imbued by the human needs and intentions that shaped the other forms of artefact, operate more conceptually. Wartofsky (1973: 209) described tertiary artefacts as follows:
The upshot, however, is that the constructions of alternative imaginative perceptual modes, freed from the direct representation of ongoing forms of action, and relatively autonomous in this sense, feeds back into actual praxis, as a representation of possibilities which go beyond present actualities.
