Small classes benefit high achievers more than others, K-3 study shows

KindergartenHigher-achieving students benefit more from small classes in the early grades than other students, according to a study in a recent issue of The Elementary School Journal. Researcher Spyros Konstantopoulos of Northwestern University re-analyzed data from the STAR study, a landmark study on the benefits of class size, to see what impact small classes had for students at different achievement levels and if small classes reduced the learning gap between high and low achievers.

“Overall, these results provided some evidence that higher achievers benefited more than other students from being in smaller classes,” he writes. While the study followed children from K-3, most of the impact from small class size occurred in K-1. The researcher adds that the results do not mean lower-achieving students are better off in regular classes and maintains that all types of students benefit from being in small classes.

“These findings suggest differential effects of small classes across different types of students, that is, some types of students benefit more than others from being in small classes,” he writes. With the smaller number of students, the gap could actually widen between high and low achievers.

In the STAR study, kindergarten students were randomly assigned to one of three treatment conditions: smaller classes (13-17 students), larger classes (22-26 students), or larger classes with a full-time classroom aide. The nearly 11,000 Tennessee elementary school students who participated in the mid 1980’s were followed through grade 3. The students were in 79 elementary schools in 42 districts. Achievement was tracked with the Stanford Achievement Test (SAT) reading and mathematics scores collected from kindergarten through grade 3.

Other researchers have re-analyzed data from the STAR study to see how class size affected low achievers, but there is weak evidence of an impact on low achievers, the researcher says. He also did not find any evidence of additional benefits of small classes for lower achievers.

“This result should be interpreted with caution,” he adds. “It does not necessarily mean that lower-achieving students are better off in larger classes because all students benefit from being in small classes.”

{Editor’s note: While STAR found benefits from small class sizes, many other studies have found little to no benefit. In research published in Educational Evaluation and Policy Analysis, Winter 2007, researchers Carolina Milesi and Adam Gamoran found that the quality of classroom instruction mattered much more than class size. They found “no evidence that class size affects reading or mathematics achievement in kindergarten.” See “Quality teaching, not class size raises student achievement“}

One purported advantage of small class size is that teachers are more likely to identify lower achievers and provide instruction designed to benefit them, but his results do not support this, according to Konstantopoulos. Another hypothesis, supported by this study, is that teachers are more likely to identify higher-achieving students in small classes and more likely to provide effective strategies that benefit these students more and that higher-achieving are better able to take advantage of learning opportunities in smaller classes.

In this study, small class size seems to have been benefited higher-achieving students in the first two grades (K-1). Other researchers have found that the cumulative effects of small classes diminish over time in mathematics, Konstantopoulos writes.

“Typically, in the first two years of schooling students learn what behaviors are expected in school. This means that teachers spend considerable time on management- and behavior-related issues. It is likely that in smaller classes these issues are addressed in a shorter time than in regular classes, and this in turn means that in kindergarten and first grade more time is spent on learning and instruction in small classes.”

“Do Small Classes Reduce the Achievement Gap between Low and High Achievers? Evidence from Project STAR,” by Spyros Konstantopolulos, The Elementary School Journal, Volume 108, Number 4, pp. 275-291.

Published in ERN April 2008 Volume 21 Number 4

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