Supporting Expository Writing through Colour-Coded Paragraph Instruction: A Single-Case, Multiple-Baseline Evaluation with Students Requiring Special Education Support

Abstract

This single-case experimental study examined the effectiveness of the colour-coded paragraph-writing intervention (CCPWI) with three fifth-grade students attending a German lower-secondary school that provides inclusive special education. All participants demonstrated adequate spelling and grammar but persistent difficulties in organizing written text. A multiple-baseline-across-participants design was employed, featuring concurrent baselines and staggered intervention onsets. Instruction followed the gradual-release model (“I do, we do, you do”) and utilized a colour-coded graphic organizer to support topic, detail, explanation, and conclusion sentences. Paragraph quality served as the dependent variable. Visual analysis revealed consistent phase changes across all three cases. Effect-size indices indicated strong improvements, with nonoverlap of all pairs (NAP) values of 94%, 89%, and 94% and Tau-U coefficients of .62, .63, and .87 for the three participants, respectively; Hedges’ g ranged from 1.20 to 1.53. Hierarchical piecewise regression showed a significant positive intervention slope, suggesting progressive growth rather than an abrupt level shift. End-of-study, one-on-one interviews reflected high social validity. Overall, findings support CCPWI as a feasible, acceptable, and effective approach for enhancing expository-paragraph structure among at-risk learners who, despite adequate foundational skills, exhibit pronounced and persistent difficulties in higher-order writing.