Does ADHD Moderate Classroom-Level Effects on Early Literacy?

Prior literature using twin pairs in the same or different classes found classroom effects accounted for between 8% and 2−3% of the variability in literacy achievement depending on the method, grade, or measure used. The current study examines whether this effect could be greater (or less) than this depending on a child’s levels of inattention and hyperactivity. The sample comprised 758 identical and same-sex fraternal twin pairs from an international longitudinal twin study of early literacy development. The study used scores on word reading, spelling and reading comprehension, and parent ratings on the Disruptive Behaviour Rating Scale (DBRS) for children in kindergarten (aged x overbar x ¯ x = 6.2, s = 0.3), Grade 1 and Grade 2. Contrary to predictions, the results failed to support the prediction, indicating that classroom-level effects are independent of the behavior issues measured in this study.