Efficacy of Small Group Reading Intervention for Grade 2 and 3 Children With Reading Difficulties: A Cluster Randomized Controlled Trial

We examined whether Phonics + Set for Variability (S fV) reading intervention would lead to better irregular word reading compared to Phonics + Morphology within a cluster randomized control trial (RCT) design with a follow-up measurement. The participants were 273 Grade 2 and 3 students with reading difficulties (139 in the Phonics + S fV and 134 in the Phonics + Morphology) who received intervention in small groups (2–4 children), 4 times a week, 30 minutes each time, for 15 weeks. Results of hierarchical linear modeling showed that there was a significant effect of intervention on all reading outcomes (e.g., from pre- to posttest the effect sizes for Phonics + S fV ranged from g = 0.74 to 1.54 and for Phonics + Morphology from g = 0.75 to 1.49). Unexpectedly, there were no differences between the intervention conditions in any of the outcome variables, including irregular word reading and morphological awareness that the interventions partly focused on.