A popular measure proposed to produce better educational outcomes in public schools today is to reduce class size. The Wichita, Kansas public school district is currently proposing a bond issue with a partial goal of reducing class size. At least some of the recently-mandated increase in school spending in Kansas was used to reduce class size.
It seems that smaller class sizes should be great for students. Research, however, doesn’t always verify this assumption. The Harvard economist Caroline Hoxby, now at Stanford, has stated this about her research into class size:
I have a study in which I examined every change in class size at every elementary school in Connecticut over a 20-year period. In schools, class size varies from year to year because enrollment varies. Therefore, with 20 years and 800-some schools, there is a tremendous amount of variation in class size to examine.
I found there was no effect of class size on achievement at all, even when children were in small classes for all six years of elementary school.
There is, however, one study that shows increased student performance with smaller class sizes: the Tennessee STAR experiment. It is probably the study cited most often by education bureaucrats, so learning a little about it is useful. In this experiment, students were assigned to either a regular class with about 24 students, a class of the same size but with a teacher’s aide to assist the teacher, or a smaller class of about 15 students.
Jay Greene has written about the problems with the STAR experiment. The first problem he finds is that “students were not tested when they entered the program. Such point-of-entry tests would establish a baseline for each student’s performance as it stood before the experiment began. Without this baseline measurement, we cannot confirm that the STAR project’s random assignment method was successfully carried out.”
Second: “[there is] an anomaly in the research findings: the improvement in test scores was a one-time benefit. … This is an unusual and unexpected finding, because if smaller classes really do improve student performance we would generally expect to see these benefits accrue over time.”
The STAR program produced a one-time improvement in tests scores that are the equivalent of a student in the 50th percentile moving to about the 58th percentile. Greene says this increase “may not amount to an educational revolution, but it is not trivial.”
One interesting aspect of the STAR program is that participants, particularly the teachers, knew they were part of an experiment. Caroline Hoxby describes the implications of this:
More importantly, in the Tennessee STAR experiment, everyone involved knew that if the class-size reduction didn’t affect achievement, the experimental classes would return to their normal size and a general class-size reduction would not be funded by the legislature. In other words, principals and teachers had strong incentives to make the reduction work. Unfortunately, class-size reductions are never accompanied by such incentives when they are enacted as a policy.
Education bureaucrats and teachers often claim that schools are not like a business or other areas of human endeavor, so incentives don’t work. Education, they say, is somehow different. But it appears in the STAR program that teachers had a powerful incentive to make the small class sizes work, and they responded to that.
Reducing class size is a very expensive measure to implement. The STAR program reduced class sizes by a large amount: from 24 to 15 students, a reduction of 38%. Many more teachers and classrooms are needed to implement reductions of this scope, and that’s why it is so expensive.
That leads to an aspect of the problem that’s not often mentioned. Right now Wichita has a teacher shortage. The district can’t hire and retain enough teachers. Implementing class size reduction programs requires more teachers and makes the shortage even more acute.
Compounding this problem is that research shows that teacher quality is a very important factor in the success of students. If we can assume that the most highly-qualified teachers are hired first, then increasing the number of classrooms means hiring more less-qualified teachers. So some students will be taught by poor teachers, and since class sizes are smaller, fewer students will be in the classrooms led by good teachers.
There is no doubt that teachers and the education establishment like smaller class sizes. Smaller classes mean an easier workload for teachers, larger budgets for school district administrators and politicians, and more teachers union members paying dues. The local board of education can tell parents that they have “saved the children” and the parents will believe them. The research, however, is not settled on the benefits of smaller class sizes, and the unintended consequence of more students being taught by less-qualified teachers is a large negative effect.