This study proposes task of teaching as an organizer of dimensionality in teachers’ subject matter knowledge for teaching (SMK) and investigates it in the context of measuring SMK for teaching high school geometry (SMK-G). We hypothesize that teachers use different SMK-G in different aspects of their teaching work and that such differences can be scaled and associated with key elements of instruction. Analyses of 602 high school teachers’ responses to two sets of items designed to measure the SMK-G used in two particular tasks of teaching—understanding students’ work (USW) and choosing givens for a problem (CGP)—suggested the two scales of SMK-G to be distinguishable and differently related to experience in teaching high school geometry.
This article is based in part on the first author’s doctoral dissertation written at the University of Michigan under the direction of the second author. The authors appreciate the advice from several anonymous reviewers. The main data corpus used in this study was collected as part of a project supported by NSF grant DRL-0918425, with additional data collected with resources from NSF grant DRL-1420102. All opinions are those of the authors and do not necessarily represent the views of the National Science Foundation.
The guest editor for this article was M. Kathleen Heid.
Inah Ko, School of Education, University of Michigan, 610 East University Ave., Ann Arbor, MI, 48109; inahko@umich.edu