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Probably few issues in education have been studied as often as class size, yet few studies have produced satisfactory or consistent results; many have reviewed class-size reductions from 40 to 30, or 30 to 25. There have been few major, controlled class-size studies. There have been even fewer that explored the 15:1 range suggested in 1978 by Gene Glass and colleagues when they wrote "Meta-analysis of research on class size and achievement" published in Educational Evaluation and Policy Analysis.

The Research Staff and Consultants at HEROS have been researching the effects of reducing class size to a ratio of 15 to 1 since 1984. Dr. Helen Pate-Bain (HEROS consultant and Board Chair) began to conduct research on the impact of reduced class size while at the Center for Excellence in the Teaching of Basic Skills to Economically and Educationally Disadvantaged Students. In the Dupont Class Size Study, she (with Ed Whittington and Ben Dennis) studied the effects of class size (1:15) on the teaching/learning process during grades 1-3 in the Metropolitan Nashville-Davidson County Schools.

The research started with an experimental group consisted of 105 first grade students divided into seven classes of 15 students each. The control group consisted of 90 students divided among three and one-half teachers with a class size of 25 students each. A blind control group was selected comprising of 105 students drawn from 35 elementary schools, matched with the experimental group demographically according to five pre-established criteria: (a) sex, (b) race, (c) economic status, (d) date of birth within 45 days, and (e) total pre-reading raw score within four point on the California Achievement Test Level 10. The statistical analysis of pre- and post-test results indicated that the experimental group consistently achieved better results than either control group. The only intervening variable was the reduction of class size from 1:25 to 1:15. Therefore, it was concluded that reducing class size to 1:15 has a positive effect on student reading and math outcomes. The research results were in reported in the article "Effects of Class Size on First-Grade Students" prepared by Ed Whittington, Helen Pate-Bain, & C.M. Achilles and published in Spectrum, Journal of School Research and Information, Fall 1985. A more detailed summary on this research will be available online from HEROS in September 1998.

In 1985, Dr. Helen Pate-Bain shared the results of the first year of her study & information on Project Prime Time in Indiana with the Tennessee State Board of Education and the House and Senate Education Committees. Based on her urging that Tennessee examine the issue of optimum class size and with the support of Rep. Steve Cobb & Sen. Doug Henry, legislation (House Bill 544) was passed to conduct a well-designed study of class size. The Tennessee State Department of Education organized to conduct the legislated study of reduced student/teacher ratio and adopted the name STAR, an acronym for Student/Teacher Achievement Ratio. Dr. Jayne Boyd-Zaharias, DeWayne Fulton, and Van Cain began their study of the class size effect in education during the course of this research.

In 1996, foundation funding permitted HEROS, Incorporated begin conducting follow-up research on the Project STAR Class Size Study. A goal of our current work has been to provide educational researchers with access to this important data. On September 1, 1998, HEROS, Incorporated began offering a public access data set from this study . The data files, definitions, and descriptors are available online at the Project STAR Data web site. You will find more detailed information on class size research, including new results from the HEROS STAR Follow-up Studies online at the Project STAR homepage here at the HEROS Website

Background Material into the Class Size Issue

Class size is among the most thoroughly researched topics in public education. Over 250 separate studies dealt with class size by 1950. Since that time related research has increased proportionately. Often cited as the beginning of the most recent era of class size research, Howard Blake's 1954 inquiry analyzed the literature on class size prior to 1950. From the 267 reports located, he chose 85 of those based on original research that dealt with elementary and secondary school students. Of these 85 studies, 35 indicated that small classes were better, 18 indicated that large classes were better, and 32 did not support either conclusion. In further analyzing these studies, Blake established criteria to test their scientific acceptability (adequacy of sample, adequacy of measurement of the independent variable, adequacy of criterion variable measurement, rigorousness of data examined and appropriateness of the conclusions). Only 22 of the 85 previously acceptable studies met these minimum requirements. Of these, 16 favored small classes, 3 favored large classes, and 3 were inconclusive.

Empirical research prior to the 1980s had not produced consistent results regarding the relationship between class size and student achievement in spite of the amount of research that has addressed this question. In 1978, the Educational Research Services published a review of 41 studies of the effects of class size on achievement, concluding that reducing class size alone would not increase student achievement. In classes of 25-34 students at the primary level, the studies show some support for the hypothesis that smaller classes are related to higher achievement in reading and mathematics, particularly if the students are socially or economically disadvantaged or remain in small classes for at least two years (ERS, 1978).

The first meta-analysis by Glass, Cahen, and Smith (1978) dealt with the impact of class size on student achievement. By combining 77 studies, which yielded 725 comparisons of achievement in classes of different sizes, they were able to spot trends that did not show up clearly in every study. An important outcome of the Glass/Smith meta-analysis was the finding that the greatest gains in achievement occurred among students who were taught in classes of 15 students or less. Glass, Cahen, and Smith (1978) summarized their findings in these words:

As class size increases, achievement decreases. A pupil who would score at about the 63rd percentile on a national test when taught individually, would score at about the 37th percentile (when taught) in a class of 40 pupils. The difference in being taught in a class of 20 versus a class of 40 is an advantage of ten percentile ranks.

A follow-up study by the Far West Laboratory for Educational Research and Development using "meta-analysis" was published in 1979. Non-achievement effects on class size such as effects on students, effects on teachers, and effects on the instructional environment and processes were investigated. The results indicated that decreasing class size had a beneficial effect on the classroom environment. In the review, class size was shown to have a more "substantial effect" on teachers than on students or the instructional environment. The effect of class size was more significant for students below the age of twelve (Smith et al., 1979).

When N. Filby and colleagues published "What happens in smaller classes? A summary report of a field study" in 1980 they reported that teacher attitudes improved in smaller classes. Teachers in reduced class size environments were able to reach a child and help him/her when the help was needed; in larger classes the teachers felt that they could not get there to help. These teachers stated that with large class assignments their workload was heavy and overburdened. When such overloading decreased, as smaller classes became a reality, the teachers were able to relax more, feel less frustrated, and were able to create a more positive learning climate that also discouraged classroom disruptions. They found that the attention rates for students increased as class size decreased. The range of those paying attention was from 56 percent in large classes to 72 percent in the smaller classes. Increased attention span meant less time waiting for help or causing disturbances in the classroom

The researchers concluded that the class size reductions alone do not necessarily bring about change. However, teachers experience improved conditions, and this development brings about greater enthusiasm on the part of the teacher. Such enthusiasm can lead to changes that benefit everyone. Teachers usually do what they are inclined to do anyway; however, smaller classes allow them to do a better job. This conclusion was supported by an earlier teacher survey. The National Education Association conducted a teacher opinion poll in 1975. It reported that more teachers named lowering class size than any other item as the one improvement that would create better teacher morale and job satisfaction. It was the opinion of these teachers that smaller classes mean that student attitudes toward learning and motivation would be more positive resulting in higher academic achievement.

A statewide reduction of classes in grades K-3 was the result of pilot data from the Indiana State Department of Education (1983). The 1981-83 study compared reading and mathematics achievement of 24 K-3 classes at a ratio of 14:1 to K-3 classes averaging 23 students. Standardized reading and math test scores showed that students in the "small" classes exceeded normal growth in greater numbers than comparable students in the "regular" classes. Generally, 14 percent more students in smaller classes exceeded the expected achievement than students in larger classes. Teachers also saw improvements in the behavior of students, increased productivity, and more hands-on participatory learning.

Research has begun to focus upon what actually happens in smaller classes as opposed to larger ones. The Ministry of Education in Ontario, Canada was concerned with this question in a two-year study. Students from the fourth grade were assigned, in the first year, to some thirty-four different classes--some with sixteen students, some with twenty-three, some with thirty, and some with thirty-seven. During the second year they were all reassigned to different sized classes. This allowed the re-searchers to study the same students and the same teachers in different settings and to observe changes in classroom processes. The overall findings indicated that even though class size did not change the degree of individualized instruction, the teacher did spend up to twice as much time per student in the reduced size classes (Klein, 1985).

In a 1986 review for Education Research Service, Robinson and Wittebols objected that the Glass and Smith findings because the meta-analysis had included college classrooms and individual tutoring arrangements. They suggested a Related Cluster Analysis approach designed to: (1) identify and summarize all of the research studies available on the effects of class size, and (2) group the research findings into clusters related to each of several major areas in which problems, issues, and decisions relating to class size are likely to occur. The advantages of this approach, according to Robinson and Wittebols, was that it sorts out from the large body of research findings on class size into those findings that relate directly to specific areas and it made the research understandable and useful for application to specific decisions. It differed from the Smith and Glass Meta-Analysis in that Meta-Analysis removes decision makers from familiarity with the research by giving them only broad generalizations. However, when Robinson and Wittebols did a cluster analysis by grade level they concluded that smaller classes were beneficial in the early primary grades. (Robinson et al., 1986).

The most comprehensive review, meticulously conducted for the California Educational Research Cooperative by David Mitchell and colleagues concluded that:

For all student populations, class size research, while difficult to synthesize offers convincing evidence of an important link between lowered student/teacher ratios and higher achievement (Mitchell, et al., 1989).

Findings from the current major well-designed class size studies, seem to have influenced policy makers toward the institution of reduced class size. Ernest L. Boyer, president of the Carnegie Foundation for the Advancement of Teaching, has laid out a four-point plan to ensure that all children are educated to their full potential, which includes reducing classes to "no more than 15 students per teacher" for the early elementary grades. In addition, the National Association of Elementary School Principals (NAESP) Delegate Assembly has revised their class size policy statement from 20 to 1 down to recommending a student-teacher ratio of 15 to 1.