This study had two purposes. The first was to explore the construct of teacher knowledge of educational technology through the lens of three components of Shulman's model of teachers' knowledge---content knowledge, pedagogical knowledge, and pedagogical content knowledge. A second purpose was to investigate the ways in which teacher knowledge was acquired, shared, and used by student teachers and their mentors during student teaching placement. The literature in educational technology takes, for the most part, a limited view of educational technology knowledge, reporting on teachers' awareness of technological applications and affordances. By using Shulman's model, this study constructed and considered a more comprehensive depiction of teacher knowledge. Data for the study were drawn from a three month observation and interview period. Six participants---three student teachers and three mentor teachers---were observed and interviewed at a middle school in a working-class suburb of a large Midwestern city. From observations of teacher practice, inferences were made about the underlying body of knowledge evidenced by the participants. The perspective of student and mentor teacher participants was gained through the interview process. Observation and interview data were analyzed using a shared coding system, allowing a rich description to be created. Results of the study indicated that employment of Shulman's model revealed a set of knowledge derived from and applicable to practice with educational technology. This knowledge could be considered a Pedagogical Content Knowledge of technology, corresponding to Shulman's identification of a particular understanding by teachers of content in service of teaching and learning. Within the context of the mentor/student teacher pairs, both knowledge acquired in and brought to the setting was shared in a multi-year cycle from student teacher to mentor to subsequent student teacher. Impact on the field includes a broadening sense of the nature of knowledge of educational technology, as well as increased attention to the importance of the student teaching placement and student and mentor teachers' roles within that environment.Ph.D.EducationEducational technologyTeacher educationUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/126011/2/3016913.pdf