“…Through additional research over the past thirty years, these knowledge bases have been expanded, more explicit subcategories have been identified and argued, and different contexts investigated, in order to demonstrate the highly nuanced phenomenon of teachers' PCK (see Exley, 2001Exley, , 2005Grossman, 1990;Grossman, Wilson, & Shulman, 1989;Hill, Rowan, & Ball, 2005;Magnusson, Borko & Krajcik, 1999;Munby, Russell, & Martin, 2001;Park & Oliver, 2008;Phelps & Schilling, 2004;Turner-Bisset, 1999;Van Driel, Verloop, & De Vos, 1998;Woolfolk Hoy, Davis, & Pape, 2006;Zembal-Saul, Krajcik, & Blumenfeld, 2002). The relationship between the categories of teachers' professional knowledge bases and PCK have been said to be interrelated and synergistic, with teachers not only employing their PCK, but blending the individual categories to plan, teach, and assess.…”