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REL Midwest Ask A REL Response


November 2021


What research resources are available on the relationship between student enrollment (that is, school size) and student outcomes?


Following an established Regional Educational Laboratory (REL) Midwest protocol, we conducted a search for research reports, literature reviews, and descriptive studies on the relationship between student enrollment (that is, school size) and student outcomes. We looked for resources at the elementary, middle, and high school levels. In particular, we focused on identifying resources related to student achievement, graduation rates, and sense of social-emotional wellbeing. For details on the databases and sources, key words, and selection criteria used to create this response, please see the Methods section at the end of this memo.

Below, we share a sampling of the publicly accessible resources on this topic. References are listed in alphabetical order, not necessarily in order of relevance. The search conducted is not comprehensive; other relevant references and resources may exist. For each reference, we provide an abstract, excerpt, or summary written by the study’s author or publisher. We have not evaluated the quality of these references, but provide them for your information only.

Research References

Abdulkadiroglu, A., Hu, W., & Pathak, P. (2013). Small high schools and student achievement: Lottery-based evidence from New York City (Working Paper 19576). National Bureau of Economic Research.

From the ERIC abstract: “One of the most wide-ranging reforms in public education in the last decade has been the reorganization of large comprehensive high schools into small schools with roughly 100 students per grade. We use assignment lotteries embedded in New York City’s high school match to estimate the effects of attendance at a new small high school on student achievement. More than 150 unselective small high schools created between 2002 and 2008 have enhanced autonomy, but operate within-district with traditional public school teachers, principals, and collectively-bargained work rules. Lottery estimates show positive score gains in Mathematics, English, Science, and History, more credit accumulation, and higher graduation rates. Small school attendance causes a substantial increase in college enrollment, with a marked shift to CUNY institutions. Students are also less likely to require remediation in reading and writing when at college. Detailed school surveys indicate that students at small schools are more engaged and closely monitored, despite fewer course offerings and activities. Teachers report greater feedback, increased safety, and improved collaboration. The results show that school size is an important factor in education production and highlight the potential for within-district reform strategies to substantially improve student achievement.”

Booth, E., Shields, J., & Carle, J. (2017). Advanced course completion rates among New Mexico high school students following changes in graduation requirements (REL 2018-278). U.S. Department of Education, Institute of Education Sciences, National Center for Education Evaluation and Regional Assistance, Regional Educational Laboratory Southwest.

From the ERIC abstract: “In 2008 New Mexico changed its graduation requirements for regular education high school students who completed more than their senior year of high school in a New Mexico public school. Students who entered high school in 2009 were the first to have to complete (pass with a D or better) at least one advanced course (a course designated by the New Mexico Public Education Department as an honors or gifted and talented course or designated by the school district as an advanced, Advanced Placement, gifted and talented, honors, or International Baccalaureate course), dual-credit course, or distance learning course. Numerous studies have shown the positive academic outcomes--such as higher high school graduation and postsecondary enrollment and persistence rates--associated with completing advanced courses. This study examines advanced course completion rates (the percentages of students who completed zero, one, and two or more advanced courses) among New Mexico public high school students in the first three cohorts subject to the state’s new graduation requirements to identify whether gaps exist in the state and across student and school characteristics… The study also found that advanced course completion rates were related to school characteristics. The percentage of students who completed at least one advanced course was higher among students at schools with a performance rating of A on the state’s A-F scale than among students at schools with a lower rating. The percentage who completed multiple advanced courses was substantially lower among students at small schools (those with fewer than 750 students) than among students at bigger schools. The gaps remained when high-performing students were examined separately. The percentage who completed at least one advanced course was lower among high-performing students at small schools than among high-performing students at bigger schools.”

Busby, A. C., Martinez-Garcia, C., & Slate, J. R. (2020). Elementary school size and student progress differences by ethnicity/race: A multiyear, Texas study. Journal of Interdisciplinary Studies in Education, 9(2), 184–210.

From the ERIC abstract: “In this investigation, the degree to which student enrollment (i.e., school size) at elementary schools was related to student progress on the State of Texas reading and mathematics state-mandated assessments was examined for White, Black, and Hispanic students. Archival data available on the Texas Academic Performance Report were analyzed for the 2013-2014, 2014-2015, 2016-2017, and 2017-2018 school years. Inferential analyses revealed the presence of statistically significant differences, with below small to small effect sizes. Large-size schools had statistically significantly higher reading and mathematics progress rates than Small-size schools in 6 of the 9 analyses for White students. In 6 of the 9 analyses, school size was not related to student progress in reading or mathematics for Hispanic students. Small-size schools had statistically significantly higher progress rates in mathematics for Hispanic students than Moderate-size schools. Large-size, Moderate-size, and Small-size schools had similar progress rates in reading and mathematics for Black students in 8 of the 9 analyses. Implications for policy and practice, as well as recommendations for research, are provided.”

DiPerna, P. (2020). Comparing ed reforms: Assessing the experimental research on nine K-12 education reforms (EdChoice Brief). EdChoice.

From the ERIC abstract: “Policymakers, experts and advocates have promoted many different types of education reform over the past few decades, but what is the evidence about the efficacy of these programs? EdChoice partnered with Hanover Research to find out what research has been conducted in nine major education reform areas focusing on outcomes related to student achievement or education attainment. The best methodology available to researchers for generating ‘apples-to-apples’ comparisons is a randomized control trial (RCT), which researchers also refer to as random assignment studies or experimental studies. For this summary only RCTs were reviewed--not studies using other methods--because experiments comparing treatment and control groups allow researchers to identify reform/policy/program effects while minimizing bias from unobservable factors. The brief shares the assessment of the RCT studies only examining two types of outcomes, either participating students’ achievement or measures of educational attainment.”

Egalite, A. J., & Kisida, B. (2016). School size and student achievement: A longitudinal analysis. School Effectiveness and School Improvement, 27(3), 406–417.

From the ERIC abstract: “Numerous initiatives by private philanthropies and the US government have supported school size reduction policies as an educational reform intended to improve student outcomes. Empirical evidence to support these claims, however, is underdeveloped. In this article, we draw on information from a longitudinal dataset provided by the Northwest Evaluation Association covering more than 1 million students in 4 US states. Employing a student fixed effects strategy, we estimate how a student’s achievement changes as (s)he moves between schools of different sizes. We find evidence that students’ academic achievement in math and reading declines as school size increases. The negative effects of large schools appear to matter most in higher grades, which is also when schools tend to be the largest.”

Note: REL Midwest was unable to locate a link to the full-text version of this resource. Although REL Midwest tries to provide publicly available resources whenever possible, it was determined that this resource may be of interest to you. It may be found through university or public library systems.

Fitzgerald, K., Gordon, T., Canty, A., Stitt, R. E., Onwuegbuzie, A. J., & Frels, R. K. (2013). Ethnic differences in completion rates as a function of school size in Texas high schools. Journal of At-Risk Issues, 17(2), 1–10.

From the ERIC abstract: “The purpose of this study was to investigate differences in high school completion rates among White, African American, and Hispanic students enrolled in different school sizes--small, medium, and large. For this causal-comparative research design, this study utilized archival data from the Texas Education Association’s Academic Excellence Accountability System. The researchers utilized a convenience sample of the state’s public high school students for the 2008-2009 (n = 527 schools), 2009-2010 (n = 606 schools), and 2010-2011 (n = 549 schools) school years. Two Friedman’s nonparametric repeated measures analysis of variance revealed no statistically significant differences among the three groups for small and medium schools for the 2008-2009 and 2009-2010 school years. However, for large schools, statistically significant differences emerged in favor of White students for both the 2008-2009 and 2009-2010 school years, representing large and moderate effect sizes, respectively. For the 2010-2011 school year, a statistically significant difference emerged among the three groups for small, medium, and large schools, in favor of White students. Implications are discussed.”

Gershenson, S., & Langbein, L. (2015). The effect of primary school size on academic achievement. Educational Evaluation and Policy Analysis, 37(1_suppl), 135S–155S.

From the ERIC abstract: “Evidence on optimal school size is mixed. We estimate the effect of transitory changes in school size on the academic achievement of fourth-and fifth-grade students in North Carolina using student-level longitudinal administrative data. Estimates of value-added models that condition on school-specific linear time trends and a variety of teacher-by-school, student, and school-by-year fixed effects suggest that, on average, there is no causal relationship between school size and academic performance. However, two subgroups of interest are significantly harmed by school size: socioeconomically disadvantaged students and students with learning disabilities. The largest effects are observed among students with learning disabilities: A 10-student increase in grade size is found to decrease their math and reading achievement by about 0.015 test-score standard deviations.”

Goldkind, L., & Farmer, G. L. (2013). The enduring influence of school size and school climate on parents’ engagement in the school community. School Community Journal, 23(1), 223–244.

From the ERIC abstract: “This study sought to examine the direct and indirect associations between school size and parents’ perceptions of the invitations for involvement provided by their children’s school in a school system that has actively attempted to reduce the negative effects of school size. Using data from the New York Public Schools’ annual Learning Environment Survey, path analysis was used to examine the role that school climate plays in mediating the relationship between school size and parents’ perceptions of invitations for involvement. Results from an analysis of middle and high school parents who participated in the annual school survey provided evidence that parents’ perceptions of safety and of respect from the school mediated the relationship between school size and perceptions of the extent of the invitations for involvement provided by the school. The indirect effect of school size via perception of safety and respect was larger than the direct effect of school size on parents’ perceptions of invitation for involvement.”

Lloyd, T., & Schachner, J. N. (2021). School effects revisited: The size, stability, and persistence of middle schools’ effects on academic outcomes. American Educational Research Journal, 58(4), 748–784.

From the ERIC abstract: “Since the early 2000s, educational evaluation research has primarily centered on teachers’, rather than schools’, contributions to students’ academic outcomes due to concerns that estimates of the latter were smaller, less stable, and more prone to measurement error. We argue that this disparity should be reduced. Using administrative data from three cohorts of Massachusetts public school students (N = 123,261) and two-level models, we estimate middle schools’ value-added effects on eighth-grade and 10th-grade math scores and, importantly, a non-test score outcome: 4-year college enrollment. Comparing our results to teacher-centered studies, we find that school effects (encompassing both teaching- and nonteaching-related factors) are initially smaller but nearly as stable and perhaps more persistent than are individual teacher effects. Our study motivates future research estimating the long-term effects of both teachers and schools on a wide range of outcomes.”

Note: REL Midwest was unable to locate a link to the full-text version of this resource. Although REL Midwest tries to provide publicly available resources whenever possible, it was determined that this resource may be of interest to you. It may be found through university or public library systems.

Nathan, J., & Thao, S. (2007). Smaller, safer, saner, successful schools (2nd ed.). National Clearinghouse for Educational Facilities.

From the ERIC abstract: “More than $20 billion a year currently is being spent to construct public schools. Hundreds of billions are being spent to carry out public education. Everyone wants the best possible use of that money. Families want safe, nurturing, challenging, and effective schools for their children. Community members and policy-makers want schools to be successful, and to make efficient use of their tax dollars, regardless of how much is spent. This booklet is designed to help make those things happen, by giving readers opportunities to learn from some of the most effective, innovative district and charter public schools in the country. We can make significant progress toward what Americans want by using ideas from the finest small schools and schools that share facilities. This report combines profiles of district and charter public schools from all over the United States with a research summary, showing how educators and community members have created these schools. Because more than 50,000 people ‘downloaded’ or purchased a copy of the original, 2001 report, the authors have revised and updated this edition. The report provides brief case studies of 22 public school buildings in 11 states: (1) Arizona; (2) California; (3) Colorado; (4) Connecticut; (5) Illinois; (6) Massachusetts; (7) Minnesota; (8) New York; (9) Ohio; (10) Rhode Island; and (11) Texas. These buildings house almost 50 schools and social service agencies. The profiles that follow represent urban, suburban, and rural communities throughout the United States. These schools serve a vast array of youngsters. They are united in their ability to improve achievement and behavior in safe, nurturing, stimulating environments. The key conclusions of this report are: (1) Smaller schools, on average, can provide: (1) a safer place for students; (2) a more positive, challenging environment; (3) higher achievement; (4) higher graduation rates; (5) fewer discipline problems; and (6) much greater satisfaction for families, students, and teachers; and (2) Schools that share facilities with other organizations can offer: (1) broader learning opportunities for students; (2) high quality services to students and their families; (3) higher student achievement and better graduation rates; and (4) ways to stretch and make more efficient use of tax dollars.”

Sandy, J., & Duncan, K. (2010). Examining the achievement test score gap between urban and suburban students. Education Economics, 18(3), 297–315.

From the ERIC abstract: “Data from the National Longitudinal Survey of Labor Market Experience for Youth (1997 cohort) are used to examine the urban school achievement gap. Specifically, we use the Blinder-Oaxaca technique to decompose differences in Armed Services Vocational Aptitude Battery scores for students who attended urban and suburban schools. We find that approximately 75% of the gap in this achievement measure is explained by the high concentration of disadvantaged students in urban schools. Broken down further, 36% of the gap can be attributed to differences in family background. The lower income of urban families alone explains 25% of the gap. Differences in measures of school quality, such as small classes, large schools, and private school attendance, explain very little of the gap. While current policy focuses on schools and school reform, our results are a reminder that meaningful efforts to improve performance in urban schools must address socioeconomic conditions in urban areas.”

Note: REL Midwest was unable to locate a link to the full-text version of this resource. Although REL Midwest tries to provide publicly available resources whenever possible, it was determined that this resource may be of interest to you. It may be found through university or public library systems.

Schwartz, A. E., Stiefel, L., & Wiswall, M. (2012). Do small schools improve performance in large, urban districts? Causal evidence from New York City (Working Paper 01-12). Institute for Education and Social Policy.

From the ERIC abstract: “We evaluate the effectiveness of small high school reform in the country’s largest school district, New York City. Using a rich administrative dataset for multiple cohorts of students and distance between student residence and school to instrument for endogenous school selection, we find substantial heterogeneity in school effects: newly created small schools have positive effects on graduation and some other education outcomes while older small schools do not. Importantly, we show that ignoring this source of treatment effect heterogeneity by assuming a common small school effect yields a misleading zero effect of small school attendance.”

Wyse, A. E., Keesler, V., & Schneider, B. (2008). Assessing the effects of small school size on mathematics achievement: A propensity score-matching approach. Teachers College Record, 110(9), 1879–1900.

From the ERIC abstract: “Background: Small schools have been promoted as an educational reform that is capable of improving student outcomes. However, a survey of the research on small schools indicates that much of the movement for decreasing school size is based primarily on correlational methods that do not control for selection effects in the data. In addition, several recent studies have suggested that smaller schools may be able to increase student attendance and graduation rates but that these gains might not necessarily translate into gains in student achievement. Purpose: This study investigates the potential effect of attending smaller schools on student mathematics achievement using propensity score matching techniques. Research Design: Data in the study are from the Educational Longitudinal Study of 2002 and represent over 12,000 high school students. Observed student responses from 10th and 12th grade are used in the analyses. Data Collection and Analysis: An estimate of the potential effect of attending smaller schools is determined by matching students in the largest schools to smaller schools of four different sizes using propensity score matching techniques. These methods are used to attempt to account for selection effects present in these data and to approximate what the effect of attending a smaller school would be in each case. Results: Results from the study suggest that simply switching students to smaller school environments does not necessarily raise the mathematics achievement of students in the largest schools. Further analysis indicated that there did not appear to be an optimal range of school sizes that would provide maximum levels of student mathematics achievement. Conclusion: This study suggests that creating smaller schools might not be the best mechanism to raise student achievement. It is suggested that policy makers make careful deliberations before deciding to invest in small schools as an educational reform, because it is hard to establish when they will or will not be successful. Further research is needed into what makes some small schools effective.”

Note: REL Midwest was unable to locate a link to the full-text version of this resource. Although REL Midwest tries to provide publicly available resources whenever possible, it was determined that this resource may be of interest to you. It may be found through university or public library systems.

Zoda, P., Combs, J. P., & Slate, J. R. (2011). Elementary school size and student performance: A conceptual analysis. International Journal of Educational Leadership Preparation, 6(4).

From the ERIC abstract: “In this article, we reviewed the empirical literature concerning the relationship between school size and student performance with a focus was on determining the extent to which school size, specifically elementary school size, was related to student academic achievement. Most of the extant literature was on secondary school size with fewer studies published on elementary school size and even fewer studies published on middle school size. In this review, we provide a critical analysis of the available research on school size. Moreover, the benefits and disadvantages of small versus large schools were analyzed. Despite an abundance of published research studies, definitive answers regarding school size and student performance remain unanswered. Decisions about school size appear to be complex and involve a variety of factors such as costs, community support, and students with special educational needs.”


Keywords and Search Strings

The following keywords and search strings were used to search the reference databases and other sources:

  • “Optimal school size”

  • “School size”

  • “School size” “academic achievement”

  • “School size” “enrollment”

  • “School size” “school effectiveness”

Databases and Search Engines

We searched ERIC for relevant resources. ERIC is a free online library of more than 1.6 million citations of education research sponsored by the Institute of Education Sciences (IES). Additionally, we searched IES and Google Scholar.

Reference Search and Selection Criteria

When we were searching and reviewing resources, we considered the following criteria:

  • Date of the publication: References and resources published over the last 15 years, from 2006 to present, were include in the search and review.

  • Search priorities of reference sources: Search priority is given to study reports, briefs, and other documents that are published or reviewed by IES and other federal or federally funded organizations.

  • Methodology: We used the following methodological priorities/considerations in the review and selection of the references: (a) study types—randomized control trials, quasi-experiments, surveys, descriptive data analyses, literature reviews, policy briefs, and so forth, generally in this order, (b) target population, samples (e.g., representativeness of the target population, sample size, volunteered or randomly selected), study duration, and so forth, and (c) limitations, generalizability of the findings and conclusions, and so forth.
This memorandum is one in a series of quick-turnaround responses to specific questions posed by educational stakeholders in the Midwest Region (Illinois, Indiana, Iowa, Michigan, Minnesota, Ohio, Wisconsin), which is served by the Regional Educational Laboratory (REL Midwest) at American Institutes for Research. This memorandum was prepared by REL Midwest under a contract with the U.S. Department of Education’s Institute of Education Sciences (IES), Contract ED-IES-17-C-0007, administered by American Institutes for Research. Its content does not necessarily reflect the views or policies of IES or the U.S. Department of Education nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.