One influential educational evaluation is the Tennessee STAR experiment, a large-scale randomized study that examined whether reducing class sizes in kindergarten through third grade improved student learning. The evaluation demonstrated that students placed in small classes of about 13–17 students showed higher achievement in reading and math compared to peers in regular-sized classes, with especially notable gains for Black students and those from low-income backgrounds (Mosteller, 1995). A major strength of this evaluation is its randomized controlled design, which provides strong causal evidence rather than simple correlation. Additionally, long-term follow-up research showed that the advantages of early small-class placement persisted into adolescence and adulthood, influencing graduation rates and even earnings. However, the study also has weaknesses: class-size reductions are expensive to implement at scale, some variation in how schools executed the experiment introduces noise into the results, and the findings emerged in the 1980s, meaning modern contexts—technology integration, curriculum changes, and shifting demographics—may influence how well the results generalize today. Still, STAR remains a landmark evaluation because it demonstrates how rigorous research can guide practical decisions about resource allocation in education.

Reference:

Mosteller, F. (1995). The Tennessee study of class size in the early school grades. The Future of Children, 5(2), 113–127.