The Benefits Of Cutting Class Sizes

New evidence from the United States suggests that class sizes of around 15 pupils for children aged between 5 and 8 years old (American grades K-3) significantly increase the likelihood that they will end up going to university. What is more, this beneficial effect of smaller classes on aspirations to enter higher education is particularly strong for pupils from minority backgrounds. Indeed, it reduces the gap in educational performance between black and white children by more than half.

Writing in the latest issue of the Economic Journal, Professors Alan Krueger and Diane Whitmore find that children who attended a small class (between 13 and 17 pupils) in the early grades score higher on standardised tests and are more likely to take the ACT or SAT college entrance exam, a standard requirement for most US colleges. The effects are particularly strong for minority pupils and those entitled to a free or reduced-price lunch. Most significantly, being assigned to a small class appears to narrow the black-white gap in college test taking by 54%.

The researchers have analysed Project STAR, an experiment in 79 Tennessee public (i.e. state) schools in which 11,600 schoolchildren and their teachers in grades K-3 were randomly assigned to a small class (13-17 pupils), a regular size class (22-25) or a regular size class with a teacher aide. The experiment began with kindergarten (grade K) children in the 1985/6 school year. After four years, all children were returned to regular size classes. Project STAR children who moved along on pace graduated from high school in the spring of 1998.

To determine the impact of having attended a smaller class in elementary school on children''s longterm educational outcomes, the researchers examined information on whether high school seniors (final year schoolchildren) in the class of 1998 who had been in Project STAR took either the SAT or ACT college entrance exam. This is the first database that permits a long-term examination of the behaviour and post-high school aspirations of Project STAR participants.

The main results are illustrated in the chart below. This reports the percentage of pupils who took either the ACT or SAT exam by the type of class they were assigned to attend in their initial year in Project STAR. For the entire sample, the chart indicates that 43.7% of schoolchildren who were assigned to a small class took either the ACT or SAT exam compared to 40% for those assigned to a regular size class and 39.9% for those assigned to a regular size class with an aide. The 3.7 percentage point higher test-taking rate for those in the small classes relative to those in regular size classes is statistically significant: it is unlikely to have occurred by chance.

Note: Figure shows percent of students who took either the ACT or the SAT exam, by their initial clas-size assignment. Sample consists of 9.397 STAR students who were on grade level. Free lunch group includes students who ever received free or reduced-price lunch in grades K-3.

The chart also indicates that attending a small class was particularly effective in raising the proportion of black pupils who took a college entrance exam. Only 31.7% of black pupils in regular size classes took one compared to 40.2% of black pupils in small classes. To gain some perspective on the magnitude of this effect, note that the black-white gap in taking a college entrance exam was 13.3 percentage points for pupils in regular size classes, and 6.1 percentage points for pupils in small classes. Thus, attending a small class reduced the black-white gap in the college entrance test-taking rate by 54%.

Nation-wide, 65.8% of white and 55.3% of black young high school graduates enrolled in college within 12 months of graduating from high school in 1996. The 10.5 percentage point black-white gap in college enrolment for the nation as a whole is close in magnitude to the racial gap in college entrance exam-taking rates in regular size classes in Tennessee.

Earlier research on Project STAR has found that minority pupils and pupils entitled to a free lunch exhibited the greatest gains in test scores as a consequence of attending a small class. The findings in this chart complement a result that has been found consistently throughout Project STAR: minority pupils benefited most from attending a small class, and small classes were able to narrow considerably, though not eliminate, the gap in educational performance between black and white pupils.

Class size may not have to shrink to 15 for smaller classes to raise the likelihood that pupils take the ACT or SAT exams. Children who were initially assigned to a class of 21-25 in their first year in Project STAR were more likely to take the ACT or SAT exam than those assigned to classes of 26-30. And children in classes of 16-20 were more likely to take the ACT or SAT exam than those in classes of 21-25.

How many pupils who took the ACT or SAT exam have actually enrolled in college or how many years of higher education they will ultimately complete is not known. But based on an analysis of the High School Class of 1972 Database, these researchers have found that high school seniors who took the ACT or SAT exam completed an average of 1.63 more years of schooling than pupils who did not take one of the college entrance exams, after controlling for race and gender.

''The Effect of Attending a Small Class in the Early Grades on College-Test Taking and Middle School Test Results: Evidence from Project STAR'' by Alan Krueger and Diane Whitmore is published in the January 2001 issue of the Economic Journal. The authors are at Princeton University.