Elsevier

International Journal of Educational Research

The paradox of reducing class size and improving learning outcomes

Abstract

This paper addresses four questions: What are the effects of reducing class size? How important are these effects? How can we explain these effects? and How can we improve the outcomes when class sizes are reduced? A major aim is to provide directions for resolving the paradox as to "Why reducing class size has not led to major improvements in student learning?" and the conclusion is that class size reductions can lead to worthwhile increases provided certain conditions are met.

Introduction

It is not difficult to find claims for both sides of the argument about whether or not reducing class sizes leads to enhancements in learning outcomes. One side argues that reducing class size leads to more individualized instruction, higher-quality instruction, greater scope for innovation and student-centered teaching, increased teacher morale, fewer disruptions, less student misbehavior, and greater ease in engaging students in academic activities. On the other side, there is a voluminous literature that does not support the claim that learning outcomes are enhanced when class sizes are reduced. A major aim of this paper, therefore, is to resolve these competing claims and to offer an explanation as to how learning outcomes can be enhanced in smaller classes, and to suggest why indeed this is not currently the case.1

Section 1 of this paper will outline findings from the many studies on the influence of class size, and conclude that there is little evidence for major effects on student learning. There are probably few other domains of educational endeavor where there are such clear systematic findings of a close to zero relationship—the variance in studies is surprisingly small, and similar findings have been consistently found over the past 100 years. The earliest empirical studies were published at the turn of this century (Rice, cited by Cram, 1968), although there are earlier claims in the Talmud that the maximum size of bible classes should be 25 students. As early as 1974, Jamison, Suppes, and Wells reviewed this literature and found that 35 studies favored smaller classes, 32 were inconclusive, and 18 favored larger classes. They concluded that reducing class sizes may only "slightly" improve achievement (Jamison, Suppes, & Wells, 1974; see also Blake, 1954; Fleming, 1959; Sitkei, 1968). Hanushek (1998, p. 36) aptly sums up this literature by saying "Most discussions of reducing class size begin with an assertion that student performance will increase if only class sizes can be reduced, a proposition shown to be generally erroneous". It seems hard to reconcile the obvious—reducing class size enhances the time per student—with the evident—there is limited evidence to support the positive claims.

The claims defended in this paper are that

(a)

the results are systematically small (and not that they are centered on zero);

(b)

that there is much difficulty in reconciling the small effects with the rhetoric about the positive and, for many, obvious profound effects;

(c)

the effects of those supporting lower class sizes are more related to teacher and student work-related conditions, and the claims of those not supporting lower class sizes are more related to the small effects on student learning;

(d)

the effects of reducing class size may be higher on teacher and student work-related conditions which then may or may not translate into effects on student learning;

(e)

we should trust past evidence (which is what literature reviews and meta-analyses are based on) as indicative of what has been;

(f)

if we cannot stop the tide of parent and teacher lobbying for smaller class-sizes then it is imperative that there is a public demonstration of consequential effects when compared to other interventions that are more likely to enhance student learning.

The major arguments in this review are that a synthesis of meta-analyses and other studies of class size demonstrate a typical effect-size of about 0.1–0.2, which relative to other educational interventions could be considered "small" or even "tiny", especially in relation to many other possible interventions—and certainly not worth the billions of dollars spent reducing the number of children per classroom. The more important question, therefore, should not be "What are the reasons for this enhanced effect-size?", but "Why are the effect-sizes from reducing class size so small?" It is suggested that the reason for these small effect-sizes relate to teachers of smaller classes adopting the same teaching methods as they use in larger classes and thus not optimizing the opportunities presented by having fewer students. Most importantly, the concept of excellence in teaching in a class of 30–80 is not appropriate for discussing excellence in teaching in a class of 20–30, and similarly excellence in teaching a class of 20–30 is not appropriate for a class of 15–20.

Section snippets

The evidence

the basic cause of failure in reading, as well as in other subjects, is the large class" (Gates, 1937, cited in Douglass & Parkhurst, 1940, p. 217).

Teachers advocated for a reduction from 42 to a more reasonable 30–35 (National Education Association, 1939, cited in Douglass & Parkhurst, 1940)

There have been many studies asking the most simple and critical question—"What is the effect of reducing class sizes?" The following section outlines some of the more important studies that have addressed

Cost–benefit analyses

One way to address the importance of this 0.10–0.20 effect-size is to undertake a cost–benefit study. For example, Buckingham (2003) estimated that the effects of reducing the overall average ratio of New Zealand primary and secondary students by one student (to 18.4 and 14.5, respectively) was around NZ$113 million per year. While noting that this ratio is not the same as reducing class size, this cost only provides for one less student per class on average, it would be an ongoing commitment,

Why is this difference so small?

It seems ironic that the list of reasons as to why smaller classes are more effective is very long, but so little research is undertaken asking why the differences are so small? Further, the expected differences seem more related to quantity than quality (e.g., more on-task behavior, less student–student interactions), and there is little, if any, evidence that the fundamental nature of teaching differs when there are smaller classes (even when the same teacher is teaching small and large

A resolution to this seeming paradox of reducing class sizes and tiny effects on increasing student learning

The major claims so far are that the effects of reducing class size are tiny, which should not be surprising when teachers appear to not change their teaching behaviors even when provided with opportunities in smaller classes to teach in different ways. I wish to advance a series of arguments that may assist in moving the literature forward away from "What are the effects of reducing class sizes?" and "Why the small effect-sizes?" to "What are the conditions for optimizing student learning in

Conclusions

When addressing the issue of reducing class size, it seems important to investigate the underlying motivations for teachers and parents. For example, the synthesis of meta-analyses indicated that the presence of disruptive students (even one of them) in a class has the effect of decreasing achievement by 0.79—which is enormous. When I ask teachers if they would choose between a class size of 15 when I choose the students, or a reduction of 5 from their current class and they choose the

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