This case study instantiates longitudinal change over a two year period by examining the role of School Situated Sustained Professional Development (SSSPD) on the evolution of the participant's practice. The participant was a secondary science teacher who emerged as an exemplar in integrating Technology Enhanced Formative Assessment (TEFA) pedagogy into her practice, which was facilitated by personal response systems (PRS). The research question was: What could be revealed about the impact of SSSPD by studying teacher learning of a teacher who emerged as an exemplar? The participant was one of ten teachers learning the TEFA pedagogy. Professional development (PD) that facilitates change in teachers' practice and that sustains those changes over time is critical. Findings were triangulated from seven quantitative and qualitative data sets including monthly surveys, lesson observations, journal entries, interviews and action research sessions. The major findings of the study were: (1) implementing TEFA led to changes in the participant's practice, and (2) the SSSPD model was instrumental in the participant learning how to implement TEFA. Findings also revealed changes in the participant's beliefs, teaching strategies and in her modification of TEFA. Eight elements of teacher change were identified which were used to develop the Elements of Teacher Change in Adoption of Pedagogy (ETCAP) model. Gaining a better understanding of the SSSPD model and its potential as an effective model for PD is dependent on proving its effectiveness in promoting teacher change and sustaining that change over time.