A Meta-Analysis of the Impact of Class Size on Academic Performance in Secondary and Higher Education

A Meta-Analysis of the Impact of Class Size on Academic Performance in Secondary and Higher Education

Jane Genga-Ayiemba

Department of Education, University of Eastern Africa, Baraton

DOI: https://dx.doi.org/10.47772/IJRISS.2025.903SEDU0224

Received: 09 April 2025; Revised: 15 April 2025; Accepted: 19 April 2025; Published: 22 May 2025

ABSTRACT

This meta-analysis examines the relationship between class size and academic performance across secondary and higher education levels. Drawing on four peer-reviewed empirical studies conducted in diverse educational contexts—Rwanda, the United States, China, and the United Kingdom—this review evaluates whether smaller class sizes lead to improved academic outcomes. While each study differs in methodology, context, and performance metrics, consistent findings reveal a negative correlation between class size and academic achievement. Effect size calculations and qualitative synthesis demonstrate that smaller classes generally promote better academic performance by enhancing student engagement and instructional quality. Recommendations are made for policy reform, institutional planning, and future research, with special attention to confounding factors and recent trends in digital education.

INTRODUCTION

Class size has long been considered a fundamental determinant of student learning and academic success. The underlying assumption is that smaller class sizes allow for more individualized instruction, closer teacher-student relationships, and improved classroom management—factors believed to enhance academic outcomes. Despite this assumption, empirical findings on the topic remain mixed due to variation in educational systems, research methodologies, and outcome measures.

This meta-analysis synthesizes findings from four empirical studies examining the effect of class size in both secondary and tertiary education systems across different countries. It aims to assess the consistency of the class size effect, explore methodological and contextual nuances, and provide evidence-based insights for educational policy, classroom design, and future research.

METHODOLOGY

Study Selection Criteria

Studies included in this meta-analysis met the following criteria:

Peer-reviewed and empirical in nature.

Focused on secondary or higher education settings.

Investigated class size as a primary variable affecting academic performance.

Contained quantitative or mixed-method data suitable for synthesis.

Selected Studies

Data Extraction and Synthesis

Each study was analyzed for:

Sample size and demographics

Definition and measurement of class size

Academic performance indicators

Statistical methods used

Reported effect sizes or coefficients

Due to heterogeneity in study designs and performance metrics, a mixed synthesis approach was used; combining qualitative interpretation with effect size reporting where available.

RESULTS AND ANALYSIS

Byiringiro & Andala (2022)

Context: Rwandan public day secondary schools

Findings: Smaller class sizes improved mathematics achievement, particularly where seating arrangement and teacher interaction were optimized.

Effect: Positive correlation (r ≈ 0.45) Kokkelenberg et al. (2005)

Context: U.S. public universities

Findings: Larger class sizes significantly reduced GPA scores, with most negative effects seen in classes exceeding 20 students.

Effect: For every 10-student increase in class size, GPA decreased by 0.03 points (p < .01) Cho et al. (2012)

Context: Public elementary schools in Minnesota (Grades 3 and 5)

Findings: Smaller class sizes were associated with modest but statistically significant increases in math and reading scores.  The effect was more pronounced for disadvantaged student subgroups.

Effect Size: Reading: β ≈ -0.015, Math: β ≈ -0.018 (p < .05) per student added to class size

Interpretation: Class size reductions of 5–10 students led to measurable   academic gains, especially in lower-performing schools. Blatchford et al. (2003)

Context: U.K. schools (Key Stage 1–3)

Findings: Smaller classes in early years improved literacy and numeracy outcomes, though the effect diminished in later years.

Effect: Largest effect in Key Stage 1 (ES = 0.25); diminishing returns thereafter

DISCUSSION

Cross-Study Patterns

Despite differences in location and education level, all four studies found a negative correlation between class size and academic performance, reinforcing the idea that smaller classes benefit learning.

Instructional Quality and Engagement

Smaller classes enhance teacher-student interaction, allow for differentiated instruction, and improve behavioral management. These are particularly impactful in technical subjects and early education stages.

Confounding Variables

Several potential confounders merit consideration:

Socioeconomic status (SES): Students from lower-SES backgrounds may benefit more from small class sizes due to greater needs.

Teacher quality: High-caliber teaching can mediate or exacerbate the effects of class size.

Institutional resources: Well-funded schools are more likely to implement smaller class policies effectively.

METHODOLOGICAL LIMITATIONS

Heterogeneous metrics (GPA, test scores, literacy benchmarks) complicate direct comparison.

Effect size reporting was inconsistent across studies.

Temporal variability and differences in national curriculum standards add complexity to generalizability.

Educational Developments

Recent trends such as blended learning, personalized instruction through AI, and flipped classrooms may interact with class size dynamics in unforeseen ways. These innovations could either mitigate or amplify class size effects, depending on implementation fidelity and digital infrastructure.

CONCLUSION

This meta-analysis provides compelling evidence that smaller class sizes are generally associated with better academic performance in both secondary and tertiary education contexts. The findings are consistent across multiple countries and methodologies, indicating a broadly applicable principle in education policy and pedagogy.

However, class size should not be considered in isolation. Quality of instruction, socioeconomic factors, and access to resources must also be addressed to maximize student achievement.

Implications for Policy and Practice

Policymakers should prioritize investments in hiring more teachers and expanding classroom infrastructure.

Educators should use small group strategies even in larger classes to simulate the benefits of reduced class size.

Institutions should experiment with hybrid models to enhance engagement in larger settings.

Recommendations for Future Research

Conduct meta-analyses including more international and recent studies.

Standardize outcome metrics and report effect sizes.

Investigate how emerging technologies interact with class size to affect learning outcomes.

REFERENCES

1. Blatchford, P., Bassett, P., & Brown, P. (2003). Class size and academic achievement: A study of pupils aged 7–11 years in England. British Educational Research Journal, 29(5), 709–730.
2. Byiringiro, E., & Andala, O. H. (2022). Effect of class size on the academic performance of students in mathematics in public day schools in Musanze District, Rwanda. Journal of Education, Stratford Peer Reviewed Journals. https://www.stratfordjournals.com/journals/index.php/journal-of-education/article/view/1824
3. Cho, H., Glewwe, P., & Whitler, M. (2012). Do reductions in class size raise student test scores? Evidence from population variation in Minnesota’s elementary schools. Economics of Education Review, 31(3), 77–95. https://doi.org/10.1016/j.econedurev.2011.11.008
4. Kokkelenberg, E. C., Dillon, M., & Christy, S. M. (2005). Class size and student achievement in higher education. Cornell Higher Education Research Institute (CHERI). https://ecommons.cornell.edu/items/fdf9ce53-d846-4b23-a551-78730bc4b0b9