From Online Video-Based Professional Development to Differentiated Teaching: A Case Study of Mathematics Teacher

Video-based teacher professional development (TPD) offers teachers structured opportunities to examine their classroom practice, yet its role in supporting differentiated instruction (DI) in fully online formats remains underexplored. This longitudinal case study investigates how participation in a facilitated, fully online video-based TPD was associated with changes in the cognition and classroom practice of one lower-secondary mathematics teacher, with a specific focus on DI. Drawing on Major and Watson’s four-dimensional model of teacher cognitive change, we analyse developments in the teacher’s self-efficacy, self-evaluation, knowledge of teaching, and instructional beliefs, and link these to observable changes in differentiated classroom practice. Data were collected through six classroom observations, as well as a semi-structured interview focused on DI. The findings show that sustained engagement in structured video reflection and online professional learning community discussions supported a shift from predominantly teacher-centred instruction to more adaptive, student-centred teaching characterised by tiered tasks, embedded scaffolding for struggling students, enrichment for advanced learners, and increased collaborative problem solving.