What is a "Just-Right" Class Size in Public Schools?

This post is adapted from my book, A Parent's Guide to Public Education in the 21st Century, now available in print and Kindle versions.

Class size matters. Class size matters because it is an issue that impacts the lives of the children in the classroom, the work load of the teacher and the school budget. Teachers and their representatives argue for smaller class sizes, while school boards try to balance parent and teacher desires for small classes, with the demands of keeping the budget under control. Apparently, private schools think class size matters. They advertise small class size in an effort to attract students to their schools.

Intuitively, most parents and teachers think class size matters, but from a research standpoint the impact of class size has been harder to pin down.  At the heart of the argument is the question, “Do the academic gains achieved through smaller class sizes justify the cost of hiring more teachers to accommodate those lower class sizes?” Some education reformers have even suggested that children would be better off if schools would identify their best teachers and then pay those teachers more to accept more students in their classes.

A research study done in Tennessee is considered the gold standard of class size studies because of its rigorous experimental design. This so-called STAR study(1995) found that students in small classes learned more than students in larger classes and were more likely to complete school and attend college, but those small classes were so small that the STAR study simply rekindled the cost/benefit debate.

More recently, Northwestern University professor Diane Whitmore Schanzenbach published a study through the National Education Policy Center that summarized what we know about class size. Considering all the research as a whole Schanzenbach concluded that

·         Class size is an important determinant of student outcomes, and one that can be directly determined by policy.

·         The evidence suggests that increasing class size will harm not only children’s test scores in the short run, but also their long-run human capital formation. Money saved today by increasing class sizes will result in more substantial social and educational costs in the future.

·         The payoff from class-size reduction is greater for low-income and minority children, while any increases in class size will likely be most harmful to these populations.

·         Policymakers should carefully weigh the efficacy of class-size policy against other potential uses of funds. While lower class size has a demonstrable cost, it may prove the more cost-effective policy overall (NEPC, 2014).

So, class size does matter and it matters especially for low-income and minority children and it is likely to be worth the taxpayers’ money to attempt to keep class sizes down.

Research does not help us much with what the ideal class sizes should be. The STAR study targeted class sizes of 13-17 children, which may be out of the financial reach of many districts. As a school district administrator several years ago, I was tasked with developing target ranges for class sizes for a suburban school district. After reading the available research and consulting with the budget office, I came up with the following recommendations based on students in an affluent community.

            Recommended Class Sizes by Grade Range 

in Affluent School Districts

K-2                  20-22

 3-8                   23-25

 9-12                 23-27

If I were making these recommendations for a school district with a high concentration of students living at or near the poverty line the guidelines would be different.

 Recommended Class Sizes by Grade Range

 in High Poverty School Districts

K-2                  17-19

 3-8                   20-22

 9-12                 23-25

Courses designed for students with special needs or for students who need focused instruction on certain skills should be smaller, normally about 8-12 students.

I would recommend that school leaders, teachers and parents look at these recommendations as broad guidelines and not set in stone. A variation of a student or two from these numbers does not mean that students are necessarily being disadvantaged, but large deviations may be of concern.

To be effective, smaller class sizes require that teachers use less "stand and deliver" type of instruction. Teachers can take advantage of having fewer students in the class by having more small group work, more one-to-one conferences and more targeted attention to the individual needs of students.

For more information on class size issues, please see Leonie Haimson's wonderful website Class Size Matters.