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Doctoral Dissertation Defense
of
Amie A. Lawrence

For the Degree of
Doctor of Education
Interprofessional Leadership

Bridging the Reading Gap: Using Peer-Mediated Constant Time Delay to Improve Vocabulary and Comprehension for Middle School Students with Disabilities

July 7

Microsoft Teams

Bridging the Reading Gap: Using Peer-Mediated Constant Time Delay to Improve Vocabulary and Comprehension for Middle School Students with Disabilities

The purpose of this study was to evaluate a combined peer-mediated instruction (PMI) and constant time delay (CTD) vocabulary intervention for eighth-grade students with high-incidence disabilities. Conducted in an inclusive classroom within a rural Midwestern school, the study examined effects on proximal vocabulary acquisition and distal reading comprehension. A modified single-case hybrid Repeated Acquisition Design (RAD) was used with five students over nine weeks. Identical 10-word vocabulary sets were delivered via peer dyads three times per week during the intervention phase. Outcomes were analyzed using visual analysis, Tau-U indices, and Between-Case Standardized Mean Difference (BC-SMD) effect sizes.

Findings showed varied increases in taught vocabulary acquisition and steeper learning slopes during the intervention phase. This growth was paired with high student procedural fidelity, demonstrating that middle schoolers can accurately run the CTD protocol. Conversely, distal reading comprehension scores via FastBridge measures showed null to modest changes. The data highlighted a clear difference between proximal vocabulary gains and the gradual growth needed to improve distal comprehension within a limited window.

The results of this study offer a scalable, cost-efficient mechanism for evidence-based vocabulary differentiation in inclusive secondary classrooms. By utilizing structured peer dyads, the intervention reduces reliance on limited adult staffing resources. These findings provide critical insights for administrators and special educators, informing local practices centered on educational equity and sustainable literacy support for students with disabilities.