As school systems continue to deal with overcrowding, the debate over the impact of class size continues.

As school systems continue to deal with overcrowding, the debate over the impact of class size continues. Some policymakers are skeptical of class size reduction efforts and promote improving teacher quality as a less expensive and more effective reform. Mitt Romney has gone so far as to claim teachers unions only support smaller classes in order to grow their ranks, but parents and teachers point to a wealth of evidence that class size does matter to school and life success, especially for the most vulnerable students.

The Tennessee Student/Teacher Achievement Ratio (STAR) study, a longitudinal study begun in the 1980s, provided strong support for the argument that reducing class size to 13-17 kids in grades K-3 positively affects low-income and minority students. Smaller classes led to an 18 percent increase in graduation rates for students receiving free lunch, and analysts predicted class size reduction could help close the black-white achievement gap. However, a recent reanalysis of the Tennessee STAR study found that class size reduction did not reduce achievement gaps among classmates in any given classroom.

Romney and other skeptics of class size reduction efforts concede that class size does have some effect on student achievement. They note, however, that reducing class size is an expensive way to increase student achievement, especially considering the fact that gains from smaller classes are moderate compared with gains from improving teacher quality.

The STAR study, cited by people on both sides of the debate, compared small classes of 13-17 students with full-size classes of 22-26. As education budgets shrink, class sizes across the US are expanding beyond full-size to overcrowded. There is not yet much research on the effects of overcrowding in schools, but existing evidence suggests packed classrooms and schools demoralize teachers and hurt a student's chances at success.

Gretchen Krebs has taught general and special education in New York and Utah. She is passionate about finding innovative approaches to meet the needs of all students. Contact her at