Effect sizes can be interpreted in a meaningful context by benchmarking them against typical growth for students in the normative distribution. Such benchmarks are not currently available for students in the bottom quartile. This report remedies this issue by providing a comparative context for interventions involving these students. Annual growth effect sizes for K–12 students were computed from nationally normed assessments and a longitudinal study of students in special education. They reveal declining growth over time, especially for reading and math. These results allow researchers to better interpret the effects of their interventions and help practitioners by quantifying typical growth for struggling students.
Scammacca, N., Fall, A. M., & Roberts, G. ( 2015). Benchmarks for expected annual academic growth for students in the bottom quartile of the normative distribution. Journal of Research on Educational Effectiveness, 8, 366–379. doi:10.1080/19345747.2014.952464