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.
ENDS
Note for Editors: '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.
For Further Information: contact Alan Krueger on 001-609-258-4046 (email:
Krueger@princeton.edu); Diane Whitmore on 001-609-258-2363 (email:
Whitmore@princeton.edu); RES Media Consultant Romesh Vaitilingam on 0117-983-9770 or
07768-661095 (email: romesh@compuserve.com); or RES Media Assistant Niall Flynn on 020-
7878-2919 (email: nflynn@cepr.org).