NEPC Review: Small Class Sizes for Improving Student Achievement in Primary and Secondary Schools:

For more than four decades, researchers have worked to identify CSR’s effects in a range of school settings and for various student groups, making the reform one of the most intensive- ly studied in education research.1 A 2018 study from the Campbell Collaboration, Small Class Sizes for Improving Student Achievement in Primary and Secondary Schools by Trine Filges and co-authors, reviews available. [...] Finally, the limits imposed by the inclusion criteria make it impossible to conduct a mean- ingful meta-analysis as the review intends.3 The purpose of a meta-analysis is to apply sta- tistical analysis to a large body of evidence in order to identify common characteristics of subsets. [...] Review of the Validity of the Findings and Conclusions It is important to note first that while achievement is an important consideration, it is far from the only one worth considering when evaluating CSR’s potential, because implemen- tation varies widely and because the strategy affects so many other outcomes.4 That said, the overall finding—that achievement is very modestly increased as class s. [...] Other unanswered questions specific to CSR policy details are also important: Given the baseline class size, how much should it be reduced for desired benefits? Reducing a class of 40 to 39 might well have a different effect from reducing a class of 20 to 19, even though the reduction of one student is the same in both cases. [...] The smaller baseline of 20 might allow the teacher to give substantively more attention to individual students, while not providing the same benefit in the larger class.7 Or, reducing a class of 40 to 30 might prompt a teacher to make changes in pedagogy that a reduction of 40 to 39 would not.