NEPC Review: Small Class Sizes for Improving Student Achievement in Primary and Secondary Schools: A Systematic Review (Campbell Collaboration, October 2018)
This systematic review of research literature estimates the impact of class size reduction on reading and math achievement, two of the many possible outcomes of reducing class size. The review surveyed all international research evidence up to 2017 and identified 10 research studies meeting its methodological standards. Beyond these studies, the review provides a comprehensive catalog of research on class size reduction, and a thorough assessment of each study’s methods. However, the study takes an extremely narrow view of what research is valid for determining the impact of reducing class size. Notably, more than 90% of studies relevant to the research question were not included. In addition, while related research has appeared in many countries, only three countries are represented in the body of evidence. The result is a very limited analysis of an already narrowed question.