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Does class size matter?

It seems obvious that smaller class sizes would be better for students and teachers alike. Parents often advocate for and seek out smaller class sizes for their children. Federal funds have been used in public school districts for the Class-Size Reduction program since 1999. As well, some private schools promote smaller class sizes as an important differentiator. In my own experience, I have preferred teaching smaller classes.

If, however, one measures "better" by academic achievement, it is not clear that class size matters much. I've read two analyses of the issue - one conducted by the U.S. Department of Education and another by education researcher John Hattie, and neither showed compelling evidence that smaller class sizes lead to better outcomes. In the U.S. Department of Education's study, researchers cited two large state studies supporting class size reductions as a way to improve student achievement. However, the results of one of these studies may not be generalizable. As well, a California study found no relationship between reduced class sizes and student achievement. Nor did that study find that teachers of smaller classes covered more curriculum (A Descriptive Evaluation of the Federal Class-Size Reduction Program). Hattie reviewed studies of several different experimental design types from four different countries. In his analysis, smaller class sizes do affect student achievement, but only by a very tiny amount. He notes that there are other changes that schools can make that have greater effects on learning (Hattie 2012). Perhaps such analyses are why DC Public Schools are not prioritizing class size reductions and why, facing budget cuts, Fairfax County Public Schools are considering increased class sizes.

What if "better" is not measured by test scores, however? In a Wisconsin study of smaller class sizes, teachers reported that they knew their students better, were able to give more individualized instruction, and experienced fewer discipline problems (A Descriptive Evaluation of the Federal Class-Size Reduction Program). Hattie's research suggested that teachers experience better working conditions when class sizes are smaller, a factor that may improve instruction and learning (2012). Teachers may also use different styles of instruction when class sizes are smaller - small group activities, hands-on activities, and writing assignments. These instructional techniques could have yet-to-be measured benefits for students.

So, is it worthwhile for parents to advocate for smaller class sizes? Should families make enrollment decisions based on class size? I would advise against making class size reduction a primary goal: I don't see enough evidence that it makes a difference in children's learning experiences. Question too what "smaller" class size means. In some cases advertised smaller classes may only offer modest reductions in the student-teacher ratio. As well, schools with significantly smaller classes may have teachers who do not use class size to greatest effect. Instead, I suggest examining the aspects of your child's education that you think might be affected by smaller class size. Ask what strategies your child's school will use to boost the achievement of all students, for example. What techniques do teachers use for classroom management, and how does the school handle discipline? If you are considering enrollment at a school that boasts of smaller class sizes, can the administration demonstrate that teachers give more individualized attention or provide learning opportunities that would not be possible within a larger class? Unfortunately, it is difficult to measure educational quality objectively. Class size may appear to be a promising metric for judging schools, but small classes may not offer the benefits we would hope for.

Hattie, J. (2012). Class Size. In Visible learning for teachers: Maximizing impact on learning. London: Routledge.

A Descriptive Evaluation of the Federal Class-Size Reduction Program. (2004, August 27). Retrieved November 6, 2015, from


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