Effectiveness of Small-Group Direct Instruction on Science Learning for Students With Mild Intellectual Disability

This study examined the effectiveness of direct instruction (i.e., explicit instruction) delivered in a small-group format on the science achievement of students with mild intellectual disability (MID) in the “Support and Movement System” unit, and evaluated maintenance, generalization, and social validity outcomes. A concurrent multiple-baseline design across skills was implemented with three eighth-grade female students attending a special education school. The intervention was delivered by a science teacher using the core components of direct instruction, including attention-getting, modeling, guided practice, and independent practice. Instruction focused on key concepts related to bones, muscles, and joints. Student performance was measured using percentage accuracy scores across the baseline, intervention, post-intervention, and maintenance phases, as well as ongoing generalization data. Social validity data were collected through structured interviews with students, parents, and their special education teacher. Results indicated that baseline performance was low and stable across all participants. Following the introduction of direct instruction, all students demonstrated substantial and stable increases in performance. These gains were largely maintained over time and generalized across different questions. Social validity findings were positive across all respondent groups, indicating that the intervention was perceived as effective, acceptable, and meaningful. Overall, the findings suggest that direct instruction delivered in a small-group format is an effective and feasible approach for supporting science learning in students with MID. © 2026 John Wiley & Sons Ltd. All rights reserved, including rights for text and data mining and training of artificial intelligence technologies or similar technologies.