Abstract
This study captures the teacher learning, understood as identity change, of John, an experienced out-of-field [OOF] teacher of mathematics undertaking a national professional development program, the Professional Diploma in Mathematics for Teaching [PDMT]. This research draws on the commognitive framework to document John's first-person mathematics-related teacher identity-a collection of stories told by John to a third party about being a mathematics teacher, and John's third-person mathematics-related teacher identity, a collection of stories told by the researcher about John's teaching practices. Data, in the form of interviews and lesson video and audio recordings, were collected over a 17 month period to elicit John's learning pathway while he participated in the PDMT. Sociolinguistic tools and thematic analysis elicited the endorsed narratives that shaped how John viewed himself as a mathematics teacher and his mathematics teaching practices and enabled the researcher to recognise consistencies and changes in John's mathematics teaching practices across the different timepoints. This methodological approach uncovered unanticipated outcomes of the PDMT that may inform the design of future professional development programs for OOF teachers of mathematics.
