Development of the Differentiated Instruction Self-Efficacy Scale and the Differentiated Instruction Strategies Knowledge and Usage Inventory

Differentiated instruction refers to the adaptation of instructional processes to students’ individual differences, such as readiness, interests, and learning styles. Teachers play the most critical role in adapting national education systems to differentiated instruction. However, valid and reliable measurement instruments for assessing teachers’ self-efficacy in differentiated instruction and their levels of knowledge and use of differentiated instruction strategies remain limited. This study aimed to develop the Differentiated Instruction Self-Efficacy Scale and the Differentiated Instruction Strategies Knowledge and Usage Inventory and to examine their psychometric properties. The study was conducted as a scale development study. The participants were 184 pre-service teachers enrolled primarily at a public university in western Türkiye. Data were analyzed using confirmatory factor analysis, second-order confirmatory factor analysis, Cronbach’s alpha, McDonald’s omega, and Average Variance Extracted (AVE). The Differentiated Instruction Self-Efficacy Scale consists of 21 items across six dimensions. The first-order model demonstrated acceptable fit, χ²(174) = 230, p = .003, CFI = .998, TLI = .998, SRMR = .041, RMSEA = .075. The second-order model also demonstrated acceptable fit, χ²(183) = 264, p < .001, CFI = .998, TLI = .997, SRMR = .043, RMSEA = .073. AVE values for the six dimensions ranged from .613 to .754, while Cronbach’s alpha coefficients ranged from .791 to .850. The Differentiated Instruction Strategies Knowledge and Usage Inventory consists of 14 items and a single dimension. The inventory demonstrated mixed model fit, χ²(77) = 295, p < .001, CFI = .989, TLI = .987, SRMR = .058, RMSEA = .124. Cronbach’s alpha and McDonald’s omega coefficients for the inventory were .936 and .939, respectively, and the AVE value was .595. The findings supported the six-dimensional first-order and second-order factor structures of the Differentiated Instruction Self-Efficacy Scale and provided evidence of internal consistency and convergent validity for both measurement instruments. In conclusion, the developed instruments can be used in future research examining differentiated instruction self-efficacy and levels of knowledge and use of differentiated instruction strategies.