Abstract
Differentiated instruction (DI) is widely promoted as a key pedagogy for inclusive education, yet measurement tools are limited for early childhood contexts where teaching is play-based and integrated. This study developed and validated two contextually grounded instruments for Singapore preschools: the Teacher Self-Efficacy in Differentiated Instruction (TSE-DI) scale and the DI Practice scale. Following theory-informed item generation and iterative expert review, a cross-sectional online survey was administered to 253 preschool teachers. Content validity evidence was established through multiple rounds of expert ratings of relevance and clarity, with acceptable item- and scale-level content validity indices and modified kappa agreement achieved prior to field administration. Using a split-sample approach, exploratory factor analysis (n = 50) and confirmatory factor analysis (n = 203) supported a two-factor structure for each scale. Both scales demonstrated high internal consistency and satisfactory composite reliability. Convergent validity was supported via average variance extracted and discriminant validity via heterotrait–monotrait ratios. The validated instruments provide psychometrically supported tools for research and professional learning, enabling more precise investigation of the relationship between TSE in DI and enacted DI practices within early childhood classrooms.