“I’m Glad I’ve Tried”: How Differentiated Instruction Reshapes Thai EFL Teachers’ Beliefs and Practices

Abstract This qualitative study explored the impact of the Differentiated Instruction (DI) professional development course on the cognition of Thai English as a Foreign Language teachers. Focused on two Thai in-service secondary school teachers, it examined how DI training influences their teaching beliefs and practices. Data were collected through interviews, reflective journals, and classroom observations. Thematic analysis showed that DI professional development shifted teaching methods from traditional to student-centered approaches, improving how teachers respond to the different needs of students. This shift changed how they viewed their role as teachers, from being a source of knowledge to a facilitator of learning, moving away from simply giving out information to scaffolding the entire learning process and leading to better interactions between teachers and students. Key to this transformation was peer feedback, reflective practice, and the practical implementation of DI in a real classroom context. The findings highlight the potential of DI training to improve English language teaching in Thailand, suggesting its inclusion in teacher education programs.