Op-ed: How Important is Class Size Really?

class size
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The OECD (Organization for Economic Development and Cooperation) ranks children across 38 countries every three years. These rankings are based upon the PISA, a test administered to 15-year-olds around the world. Most recently OECD ranked the US sixth in reading, 10th in science and 26th in math. Although it is hard to argue that the American education system is struggling to find it way, we are fortunate that education is front and center in policy debates.

In the ongoing debate about schools, class size is a galvanizing topic. There is ample research to support it as a major factor. For decades, researchers have found smaller classes, especially in primary grades, impact student achievement across all subjects.

Students in smaller classes outperform those in larger ones. Once classes exceed 15-18 students, one begins to see achievement decline and the gap grows each year a child is in a larger group. Importantly, the positive benefits of a smaller elementary class last in perpetuity. Additionally, size continues to have an impact with older students where upper-level math scores correlate as overcrowding impedes personalized attention and feedback from the teacher.

This kind of research, while clear, is misleading if taken in isolation. There is also evidence that shows class size is not a panacea. Even in small classrooms, an undertrained teacher can have a deleterious impact on student achievement.

Not surprisingly, teacher-related factors such as experience, quality of pre-service preparation, and subject mastery all tie to achievement. Research has shown that in higher-level math classes, for example, students score better when their teacher has a higher-level certification in their discipline. Training in both pedagogy and the subject is an even greater correlate.

The bottom line is no matter how exceptional you are, a classroom with too many students is hard to manage and teaching every child well is impossible. Similarly, it does not matter how small your class is, you need the training of a professional educator and the wisdom that comes from experience to maximize impact.

Perhaps the solutions are simple even if they are harder in execution.

Class size matters and we should invest in ways that increase the teaching force to enable class sizes to drop especially in urban and very rural areas where classes are largest, scores are often lowest, and teachers are hardest to come by.

The teacher is among the most important variables. Let’s shine a spotlight on pre-service teacher preparation so everyone entering the classroom has high level pedagogical and subject knowledge. Let’s go further and couple that with intensive mentoring programs so new teachers, and students by proxy, benefit from the years of experience of other educators in schools.

Every child in this country is uniquely impacted by the conditions in their classrooms. Many of these factors are within our control and we should, as a nation, lean in on those controllable factors to strive for excellence for all.


* Christopher Herman is Head of School at Garden School, a Nursery to Grade 12 Independent school in Jackson Heights, NY. He is a graduate of the University of Pennsylvania’s School Leadership Program and former adjunct faculty at St. Joseph’s University in Philadelphia. He writes and speaks often on topics relevant to education.

(Christopher Herman)