On class size (versus student-teacher ratio)

I originally wrote this piece as part of a project for Raise Your Hand: a guide for parents about what makes for a strong school. It was not included in the final printed material, and I have permission to publish it here.  

Any parent who has ever driven four children in a minivan, on a highway, in traffic, will tell you that the situation can move from happy family moment to tacit behavior management to Lord of the Flies in an instant: one child asks “why” on a repetitive loop, another has to pee, and a third declares loudly and insistently that she’s hungry. The fourth, whose opinion and conversation the parent might actually enjoy, refuses to make eye contact through the rearview mirror.

Now imagine that situation multiplied by a factor of eight to ten in both space and number of children and the resulting 32-40:1 ratio is the kind of work environment experienced by far too many public school teachers in the United States.

Despite an extensive body of research to the contrary, the perception in the United States persists that class size is irrelevant to any discussion of public education’s success or in its reform. In fact, class size does matter, as Northwestern University’s Diane Schanzenbach detailed in a February 2014 policy brief. (Schanzenbach, 1, 2014) “Research shows that students in the early grades perform better in small classes.This is especially the case for students who come from disadvantaged backgrounds.”

Schazenbach makes four policy recommendations concerning class size: “All else being equal, increasing class sizes will harm student outcomes. … Money saved today by increasing class sizes will be offset by more substantial social and educational costs in the future. The payoff from class-reduction is larger for low-income and minority children, while any increases in class size will likely be most harmful to these populations. Policymakers should carefully weigh the efficacy of class-size reduction policy against other potential uses of funds.” (Schanzenbach, 10)

In Chicago, Chicago Public Schools has taken up the refrain of Stanford University researcher Eric Hanushek, whose 1986 survey of research declared that class size doesn’t matter and whose earlier and later writings popularized the idea that teacher quality is a more effective influence on student outcomes, as measured by academic achievement on standardized tests. (Hanushek, 1986, Bracey, 8, 1996) The (mis)importance of teacher quality over classroom size or other direct effects to the classroom has been embraced by spokesperson Becky Carroll as well as by some parents throughout the system. (Chicago Tribune, 2013, CPS Obsessed, 2011)

By-and-large, however, parents and teachers are unswayed by Hanushek’s oft-quoted research, oft-quoted because it’s one of the few sources that deny the importance of class size. Although they are anecdotal, stories from the field pile up to reveal a trend in the importance of reasonably sized classrooms: a Lincolnwood teacher reported to our researcher that her 5th grade class size was “insanely high” in 2012-2013 at 26 students. Blaine P.E. teacher John Sykes reported class sizes of 27-38 at the neighborhood school. (Dai, 2014)

The body of research evidence in support of small to reasonably sized classrooms is significant. As Schazenbach writes, “the best evidence on the impact of reducing class sizes comes from Tennessee’s Teacher Achievement Ratio (STAR) experiment.” (Schanzenbach, 1) Barbara Nye followed up with the reduced-class size participants and published her findings in 1999: “The analyses described here suggest that class size effects persist for at least five years and remain large enough to be important for educational policy. Thus small classes in early grades appear to have lasting benefits.” (Nye, 1999)

What are these benefits?

Student academic achievement, social-emotional learning, and self-esteem, and enhanced school culture are a few of the positive effects of small class sizes. Even former governor Rod Blagojevich understood the importance of class size in 2006, “Smaller classes mean more individual attention for students. For teachers, it means spending less time on discipline and more time on instruction.” Nye also noted a positive effect of higher math and reading achievement for females in all grades. (Nye)

Another set of researchers, Finn and Achilles, found a positive effect on student motivation and persistence: “To demonstrate superior performance while facing new and more difficult challenges is itself evidence of continuing success.” (Finn, 105, 1999) And Ron Ferguson and Helen Ladd found in Alabama that 31 percent of predicted differences in average student achievement between districts in the top and bottom quartiles in math was explained by teacher qualifications and class sizes.” (Ladd)

Finn and Achilles also note, “The size of the class is related directly to the amount of time teachers spend on instruction and to pupils’ engagement in learning. Project STAR and other studies have confirmed this connection.” (Finn)  Parents whose children attend high-quality schools do not require such outside validation of what they already know: fewer students means that each student receives more individualized attention from his/her teacher. This opportunity for more balanced instruction and interaction counteracts some of the effects of high-needs students within a classroom. In 2008, Farkas and Duffett reported that 80 percent of surveyed teachers said that academically struggling students were likely to get one-on-one attention from teachers. (Hess, 2011)

Small to reasonably sized classes of 25 students allow teachers to reasonably manage the group as well as tailor instruction to varying levels of ability within the classroom.

“Lower class sizes…helped students obtain greater individual attention from teachers and allowed instructors more time for preparing and improving lessons.” (UI Press, 2008) This is further strengthened by Anthony Bryk’s research, as detailed in Organizing Schools, that a well-functioning, high-quality school embraces a student-centered learning climate. is supported and bolstered by reasonably sized classrooms and related teaching loads.

A quick scan of any teacher-quoted reporting in the past five years reveals that a student-centered learning climate is difficult, if not impossible, to maintain when a teacher must guide the learning of 27-38+ students at a time.

In 2007, the average elementary classroom size in the United States was 23.1 students. In Illinois, that number was 21.8. (New York Times, 2009) In CPS, it was 25.1. (CTU, 2012) In Finland, the PISA powerhouse that has become the go-to standard for progressive-minded education reformers, the average elementary class had 19.8 students in 2007. (New York Times, 2009) At Chicago’s Latin School, which enjoys generous financial support provided in part through significant tuition, class sizes are kept small and average between 14 (high school) and 21 (K). Francis W. Parker school maintains average class sizes of 18, and the University of Chicago Lab school gives elementary school children an average classroom size of 23.

Indeed, if the academically and economically advantaged students of Latin, Parker, and Lab perform better in classrooms of 18-23 students, one may extrapolate that students who come from disadvantaged backgrounds, like 85% of CPS, will do better in less-populated classrooms with more individualized attention from teachers.

In the context of the class size discussion, it is important to discern average class size or class size range from the reporting of student-teacher ratios or school-building utilization rates. Student-teacher ratios do not adequately reflect the experience of an average elementary student in an average elementary school. As Schazenbach wrote, student-teacher ratios “include special teachers who are not included in class size counts.” (Schanzenbach, 8) Jeremy Finn wrote, “Pupil-teacher ratios can camouflage many features of instruction.” (Finn, 2000) In its approach to categorizing student population demographics, the Chicago Public Schools has historically focused on total enrollments within a building, most recently expressed as school utilization rates. (Schazenbach, 8) This utilization approach effectively masks average class sizes within the district because, as Schazenbach writes, “actual classes and teachers are not easily divisible into fractions.” (Schazenbach, 8)

Schanzenbach, D.W. (2014) Does Class Size Matter? Boulder, CO: National Education Policy Center. Retrieved 19 February 2014 from http://nepc.colorado.edu/publication/does-class-size-matter
Hanushek, Eric (1989) Educational Researcher
Bracey, Gerald (1996). Setting the Record Straight
Sector, Bob, Ahmed-Ullah, Noreen S. and Richards, Alex (2013) “School closing critics question CPS’ ‘ideal’ class size of 30 students.” Retrieved 23 February 2014 from

Comments on Labowitz, R. (2011) Where to Charters Rank in the CIty? Retrieved 23 February 2014 from http://cpsobsessed.com/2011/11/18/where-do-charters-rank-in-the-city/
Bilicki, Caroline. Field notes, 19 February 2014.
Dai, S. (2014) “Overcrowded Blaine Must ‘Get Creative’ to Fulfill New CPS Gym Mandate” retrieved 2/22/2014 from http://www.dnainfo.com/chicago/20140217/lakeview/overcrowded-blaine-must-get-creative-fulfill-new-cps-gym-mandate
Nye, B., Hedges, L., and Konstantpoulos, S. (1999) “The Long-Term Effects of Small Classes: A Five-Year Follow-up of the Tennessee Class SIze Experiment.” 1999: Education Evaluation and Policy Analysis, p. 127-142.
Press release, 2006. http://www3.illinois.gov/PressReleases/ShowPressRelease.cfm?SubjectID=1&RecNum=4646
Finn, J. and Achilles, T. (1999) “Tennessee’s Class Size Study: Findings Implications, Misconceptions.” Educational Evaluation and Policy Analysis, 21: p-97-109.
Hess, Frederick M. (2011) “Our Achievement-Gap Mania” Foreign Affairs, 9.
Finn, J. p. 105
Teachers and Reform. 2008: University of Illinois Press, p. 4.
New York Times: http://economix.blogs.nytimes.com/2009/09/11/class-size-around-the-world/?_php=true&_type=blogs&_r=0
Latin, Parker, UC Lab’s websites
Finn, Jeremy D. (XXXX) “Class Size: What Does Research Tell Us?”
“Mayor Washinhgton Gets Reform Ball Rolling” Catalyst http://www.catalyst-chicago.org/catalyst-guides/reform-history/selected-articles/mayor-washington-gets-reform-ball-rolling
Abrams, Samuel E. “The Children Must Play” New Republic 28 Jan 2011


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