eBASE, effective basic services:Reducing Class Size Local Summary

Reducing Class Size Local Summary

Summary of evidence on the impact of Reducing Class Size on the educational attainment of pupils in sub-Saharan Africa


The text below is a summary of the research evidence on the impact of Reducing Class Size on the educational attainment of pupils in sub-Saharan Africa (SSA). It is an analysis of individual studies of reducing class size on educational attainment in sub-Saharan Africa. The information here is valuable for African school leaders, administrators and policy makers. It is even more valuable for parents who may be thinking of better ways to improve on the educational attainment of their children.

Effective Basic Services (eBASE) Africa developed this summary using available research evidence while also taking into consideration prominent themes arising from key informant interviews (KIIs) and focus group discussions (FGD), particularly FGD with teachers and students. The research evidence in this summary is acquired from a detailed and replicable search protocol used on a wide range of research databases – listed below – for related studies in low- and middle-income countries in general and sub-Saharan Africa in particular.

Definition of the strand

Class size can be defined as the teacher-pupil ratio or the number of students for whom a teacher is principally responsible for in a given period, typically a school year (Lewit & Baker, 1997). Evidence suggests that the smaller the size of a class, the greater the options a teacher can deploy and amount of attention each student receives. Reducing class size is reducing the number of pupils in a class (Higgins, et al., 2016).

Why is this strand important?

Throughout SSA, free primary education” policies have increased enrolment. This increased enrolment has rarely been matched with a proportional increase in teacher recruitment and training, or general improvement of educational quality. The teacher-student ratio has increased markedly in some countries more than others. Such drawbacks have consequences. For example, the African Development Bank (AfDB) estimates that many African countries have achieved universal primary education with rates above 90%. However, this achievement is characterized by low completion rates, high-grade repetition, rampant dropout rates and low attainment (UNECA, 2015). While the issues mentioned existed prior to an increased teacher-student ratio, some researchers and policymakers are of the view that a high teacher-student ratio has further exacerbated some of these problems, particularly the low attainment levels. Investigating, therefore, the relationship between class size and educational attainment is immensely important.

Research Evidence in Sub-Saharan Africa

In SSA, the research evidence pertaining to the effects of reducing class size on the academic achievements of learners is varied. While some studies show positive effects of reducing class size and learners’ outcomes, others have suggested null findings, and in some cases, negative effects.

In an analysis of national cross-sectional data collected by the UNESCO Institute of Statistics (UIS), Ruff, (2016) established that as the number of students per teacher increases, the chances of primary school completion drops. Reducing the number of students per teacher may free resources, allowing more teacher-student time and hence a greater focus on individual student learning preferences which may result in greater academic achievement for students, including those at risk. Similarly, an analysis of the effects of school resources on students’ mathematics achievement in Zimbabwe established that well-trained teachers improved test scores, however, student achievement is negatively affected if teachers are made to teach large classes” (Ndlovu, 2017).

A study investigating the dependence of the relationship between class size and learner outcomes on the school socio-economic status (SES), suggests that the effectiveness of class size reductions in improving learner outcomes may be dependent on other characteristics of the school such as teacher quality and school functionality. This implies that although reduced class sizes could be one way to improve learner outcomes, it may not be if other factors in relation to school and learning quality are not adressed (Kohler, 2020). Duflo, et. al., (2015) examined a program under which randomly selected Kenyan schools were funded to hire additional teachers on an annual contract at one quarter normal compensation rates. The study revealed no significant increase in test scores for students randomly assigned to existing classes despite a 46% reduction in class size. In contrast the attainment outcomes of pupils taught by locally-hired contract teachers did increase, though the authors suggest this may be due to the low absence rate of the contract teachers and a reduced effort of centrally-hired teachers in schools where locally recruited teachers were randomly assigned. A meta-analysis of impact evaluations to identify effective education interventions in SSA revealed low impact (an effect size of 0.10) of class size reductions on educational attainment (Conn, 2014). Furthermore, McEwan, (2014) in a meta-analysis of randomized experiments to improve learning in primary schools in developing countries revealed low, albeit significant effects of class size reductions.

In other countries of the developing world, the effect of class size is still subject to debate, and studies by different authors have yielded disparate outcomes. Investigating the effects of class size on student achievement, Asadullah, (2005) establishes that reduction in class size is not efficacious in a developing country like Bangladesh”. Meanwhile, Suryadarma et. al, (2006) suggest that too few students in a class might be as detrimental as too many students”. This therefore implies an in between optimal ratio of a class size.

From the above, it is clear that while the global evidence suggests moderate impact of reducing class size on educational attainment, the local evidence in SSA is mixed. Even where positive associations are established, the extent to which class size reduction improves attainment is in dispute, and some effects can only be seen when certain variables are controlled for within experiments.


The Millennium Development Goal 2 of universal primary education put many African nations on a path to increased school enrolment. Across many SSA countries, enrolment increased. However, overall attainment and completion rates dropped, two trends that have been attributed, although not necessarily with substantial evidence, to increased number of students per teacher.

Even where some relevant research has been conducted, the impact of class size reduction is predicated on the socio-economic status of the school and quality of teachers. Well-trained teachers were found to improve students’ scores, however scores tend to drop when the number of students per teacher increased. In addition, scores increased when students were randomly selected and allocated to be taught by locally recruited teachers.

Impact, Security, and Cost of Local Evidence

In SSA, very few robust studies have been conducted on the effects of class size on educational attainment. The available evidence in SSA reveal some conditional, albeit low positive association between class size reduction and test scores. More experiments are therefore recommended.

The available evidence is moderate and the costs are likely to be very high.

Search Terms

Class size, reducing class size, smaller class size.




Hand search


Asadullah, M. N. (2005). The effect of class size on student achievement: evidence from Bangladesh. Applied Economics Letters.

Case, A., & Deaton, A. (1999). School inputs and educational outcomes in South Africa. Quarterly Journal.

Conn, K. (2014). Identifying Effective Education Interventions in Sub-Saharan Africa: A meta-analysis of rigorous impact evaluations. Thesis – Graduate School of Arts and Science Colombia University.

Duflo, E., Dupas, P., & Kremer, M. (2015). School governance, teacher incentives, and pupil – teacher ratios: Experimental evidence from Kenyan primary schools. Journalof Public Economics.

Higgins, S., Katsipataki, M., Villanueva-Aguilera, A., Coleman, R., Henderson, P., Major, L., … Mason, D. (2016). The Sutton Trust-Education Endowment Foundation Teaching and Learning Toolkit. Education Endowment Foundation.

Kohler, T. (2020, January). Socioeconomic Status and Class Size in South African Secondary Schools. Bureau for Economic Research.

Krueger, A. B. (2003). Economic considerations and class size. The Economic Journal.

Lewit, E. M., & Baker, L. (1997). Class Size. The Future of Children.

McEwan, P. J. ( 2014). Improving Learning in Primary Schools of Developing Countries: A Meta-Analysis of Randomized Experiments. Review of Educational Research.

Ndlovu, N. (2017). School resources and student achievement: A study of primary schools in Zimbabwe. Academic Journals: Educational Research and Reviews.

Ruff, R. R. (2016). The Impacts of Retention, Expenditures, and Class Size on Primary School Completion in Sub-Saharan Africa: A Cross-National Analysis. International Journal of Education Policy and Leadership.

Suryadarma, D., Suryahadi, A., Sumarto, S., & Rogers, F. (2006). Improving student performance in public primary schools in developing countries: Evidence from Indonesia. Routledge Taylor and Francis Group.

UNECA. (2015). MDG Report 2015: Assessing Progress in Africa toward the Millennium Development Goals.
Addis-Ababa: Economic Commission for Africca.