Enacting knowledge in context : A classroom-based analysis of a pre-service teacher's practice

This study explores how a pre-service mathematics teacher mobilizes specialized knowledge while teaching three geometric concepts: similarity, homothety, and Thales' theorem. Drawing on the mathematics teachers' specialized Knowledge model and Duval's (1995) theory of registers of semiotic representation, the study examines how knowledge domains are enacted through multiple representations. Data were collected from three consecutive lessons during the teacher's practicum in a socioeconomically disadvantaged and traditionally structured classroom. Findings indicate that the pre-service teacher evidenced representational fluency and procedural clarity, particularly in the use of diagrams and gestures to convey proportional reasoning. However, conceptual generalizations and formative engagement with students' thinking remained limited. The study underscores the importance of teacher education programs in explicitly linking representational practices with epistemic goals and student reasoning, especially in socioeconomically disadvantaged contexts where systemic constraints often restrict opportunities. This research contributes to ongoing discussions on pre-service teacher development and the pedagogical demands of geometry instruction in authentic classroom settings.