Teachers’ Reflections on Their Subject Matter Knowledge Structures and Their Influence on Classroom Practice Stephen A. Bartos Illinois Institute of Technology Norman G. Lederman Illinois Institute of Technology Judith S. Lederman Illinois Institute of Technology Research has indicated that experts’ subject matter knowledge structures (SMKSs) differ from those of novices in that they contain more cross-linking, interconnections, and overarching thematic elements, characteristics that are in accordance with those espoused in current reform documents. Unfortunately, teachers’ SMKSs are not necessarily translated into classroom practice, for either novice or more experienced classroom teachers.A means to facilitate the translation of teachers’ SMKSs into practice would ensure that those desired characteristics of experts’ subject matter knowledge manifest themselves in teachers’ classroom practice. Four experienced physics teachers diagrammed their SMKSs, which were then compared to those inferred from their classroom practice. Prior to instruction, two teachers, as part of the explicit-reflective treatment, were asked to reflect at multiple time points on congruence between their SMKSs and classroom practice focusing on the presence of essential concepts, interconnections, and overarching thematic elements. No discernible difference was apparent between control and treatment groups, as teachers from both groups showed a high-degree of congruence between inferred and diagrammed SMKSs. Results further substantiate the challenges in identifying a means for both developing and facilitating the enactment of coherent, connected, and dynamic SMKSs or, in effect, accelerating teachers’ pedagogical content knowledge. From Shulman’s (1986, 1987) perspective the effective teacher needs to possess not only an adequate understand- ing of specific subject matter, but also knowledge of stu- dents, the curriculum, best pedagogical practices, and educational contexts if he or she is to positively impact student learning. As such, teachers with similar levels of content matter knowledge do not necessarily experience the same success in teaching their students (Shulman, 1987). In short, subject matter knowledge is necessary but not suffi- cient. Shulman further hypothesized that how teachers structure their subject matter knowledge may further impact its translation into practice (Shulman, 1987). To investigate these subject matter knowledge structures (SMKSs), a variety of methodologies have been employed including concept-mapping, card-sorting tasks, and other variations (e.g., Champagne, Klopfer, Desena, & Squires, 1978; Hauslein, Good, & Cummins, 1992; Markham, Mintzes, & Jones, 1994; Wallace & Mintzes, 1990). Other researchers (e.g., Gess-Newsome & Lederman, 1993, 1995; Lederman, Gess-Newsome, & Latz, 1994), in con- trast, have used more open-ended elicitations to purpo- sively avoid constraining respondents’ conceptions with a priori lists of terms or other “structural” limitations, for example. While research has indicated that experts’ structuring of their subject matter differs from that of novices, in that it is more elaborate and contains more cross-linking, intercon- nections, and overarching thematic elements (Chi, Glaser, & Rees, 1982; Markham et al., 1994), the ways that these structural variations translate into classroom practice have provided varied results (Gess-Newsome & Lederman, 1995; Lederman & Latz, 1995; Hauslein et al., 1992). Mounting evidence has also identified myriad factors that play a potential role in interfering with the translation of teachers’ subject matter knowledge into their classroom practice (Gess-Newsome & Lederman, 1993; Lederman, 1999; Jones & Carter, 2007; Kang & Wallace, 2004). In summary, the difficulty in elucidating the translation of SMKSs into classroom practice is aptly described by Lederman & Gess-Newsome (1992): The translation of subject matter knowledge or struc- tures to classroom practice, let alone practices which effectively represent and formulate subject matter in ways which make it comprehendible to others (i.e., PCK), is not automatic. Teaching is too complex an endeavor and human beings are not inanimate objects. (p. 19). There is some indication, however, that teachers with more coherent and integrated SMKSs tend to more closely reflect these structures through their classroom practice School Science and Mathematics 125