A Meta-Analytic Review of Spelling Interventions for Students With or At-Risk for Learning Disabilities

Spelling is a vital academic skill that supports students' writing and reading development (Kim, 2020). We conducted a comprehensive meta-analytic review of spelling interventions with students with or at-risk for learning disabilities (LDs) employing randomized controlled trials, quasi-experimental designs, and single-case designs. Fifty-nine studies met inclusion criteria-39 group design and 20 single-case design (SCD) studies-comprising 2,229 students in Grades K-9, the vast majority of whom were described as with or at-risk for LDs, with only one study including general education students. The studies yielded 327 spelling and word reading effect sizes that were used to answer three research questions regarding the overall average impact of the interventions on spelling and word reading outcomes, differential effects of the spelling intervention approach, and characteristics that may moderate effects. We ran four meta-analytic models on spelling interventions' effects on spelling and reading outcomes, conducted subgroup analyses on group designs for different spelling approaches, and ran meta-regression models with five covariates on group designs to examine moderating effects. Publication bias analyses were also conducted. Results indicated that group design spelling interventions had a small but significant effect on spelling (g = 0.33, 95% confidence interval [CI] = [0.26, 0.40]) and word reading (g = 0.25, 95% CI = [0.13, 0.37]) outcomes, while SCDs had a large and significant impact on spelling (between-case standardized mean difference [BC-SMD] = 2.47, 95% CI = [1.82, 3.13]) and word reading (BC-SMD = 1.52, 95% CI = [0.83, 2.21]) outcomes. Furthermore, results demonstrate that group design spelling interventions employing whole word study (g = 0.56, 95% CI = [0.41, 0.71]) and multilinguistic (g = 0.43, 95% CI = [0.25, 0.60]) approaches benefit spelling outcomes, while phonemic approaches to spelling intervention transfer to word reading outcomes (g = 0.45, 95% CI = [0.35, 0.55]). Findings highlight the need for systematic replication of spelling interventions to further understand the impact on writing and reading outcomes for students with LD.