Teaching is a highly complex activity that draws on many kinds of knowledge. Teaching is a complex cognitive skill occurring in an ill-structured, dynamic environment (Leinhardt & Greeno, 1986; Spiro, Coulson, Feltovich, & Anderson, 1988; Spiro, Feltovich, Jacobson & Coulson, 1991). Like expertise in other complex domains, including medical diagnosis (Lesgold, Glaser, Feltovich, & Wang, 1981; Pople, 1982), chess (Chase & Simon, 1973; Wilkins, 1980), and writing (Hayes & Flower, 1980; Hillocks, 1986), expertise in teaching is dependent on flexible access to highly organized systems of knowledge (Glaser, 1984; Putnam & Borko, 2000; Shulman, 1986, 1987). There are clearly many knowledge systems that are fundamental to teaching, including knowledge of student thinking and learning, and knowledge of subject matter.
Historically, knowledge bases of teacher education have focused on the content knowledge of the teacher (Shulman, 1986; Veal, & MaKinster, 1999). More recently, teacher education has shifted its focus primarily to pedagogy, emphasizing general pedagogical classroom practices, independent of subject matter and often at the expense of content knowledge (Ball & McDiarmid, 1990). For instance, different approaches towards teacher education have emphasized one or the other domain of knowledge – focusing on knowledge of Content (C), or knowledge of Pedagogy (P).