Class Size Doesn't Matter

The claim that class size has no impact on learning is a favorite of budget-cutting politicians, but the Tennessee STAR experiment—the largest randomized education study ever, with 12,000 students—proved otherwise. Students in small classes (13-17 students) outperformed those in standard classes (22-25) by 0.22 standard deviations in reading and math, an effect 20% stronger than the typical educational intervention. For disadvantaged students, the benefit was 30% larger than average, and gains persisted through high school. This concrete data buries the myth, making it costlier than #2: the 10% myth wastes no money, while oversized classes waste $3,500 per student in lost lifetime earnings.