Does Class-Size Mediate the Effectiveness of Teacher Quality Interventions? Improving Overcrowded Schools

October 3, 2016

Enrollment in primary and secondary schools in Uganda is increasing rapidly without corresponding increases in the number of schools and teachers. Researchers will study the impact of class size on teacher quality by running separate and slightly shorter teaching shifts. They will also study the effects of helping teachers with classroom management skills, and giving them non-financial performance incentives. Researchers will measure the effects of these interventions on student learning.

Research area: Education

Country: Uganda

Evaluation Sample: 200 schools

Timeline: 2012 - 2016

Intervention: Double Shifts; Teacher Guidance; Incentives, Schools

Researchers:Felipe Barrera-Osorio, Harvard University; James Habyarimana, Georgetown University; Shwetlena Sabarwal, World Bank; Innocent Mulindwa, World Bank; Pierre de Galbert, Harvard University

Partners: Harvard UniversityGeorgetown UniversityUganda National Examinations BoardInfoplus Consults, Uganda


The introduction of universal education in developing countries – be it primary or secondary -- often results in larger classes, which can have the unintended consequence of hurting learning. Education experts are seeking new approaches for ensuring students are ready and able to learn, including steps to make teachers more effective. This evaluation will test the impact of splitting up classes while giving teachers guidance, and small incentives, on better teaching. The evidence will help Ugandan policymakers decide whether to ex­pand or change their own program, while giving other countries information on whether such low-cost strategies can strengthen basic education at a time when enrollment is surging.


Uganda’s educational system is struggling in the face of the country’s explosive population growth. Each year, the number of children of primary school age increases by more than five percent, putting pressure on the education system to add classrooms and teachers to keep up. The introduction of free universal secondary education in 2007—universal primary edu­cation was introduced a decade earlier—added new pressures on the school system, leading to overcrowding in already stretched schools and classrooms. The Ministry of Education and Sports is trying to reduce overcrowding and improve learning in secondary schools by having schools operate in double shifts. While classes are smaller, because they are split into two, class time is also potentially shorter because teachers must teach two classes. At the request of the ministry, SIEF-supported researchers are evaluating whether double shifts in secondary schools, com­bined with an incentive program and more training for teachers, are improving the quality of education services.

Photo: Arne Hoel / World Bank

Intervention and Evaluation Details


Two programs are being implemented and evaluated to measure the impact on learning. One program encourages schools to adopt double teaching shifts in order to reduce class size, and the other offers teachers guidance for better performance and small rewards for improvements in student test scores. The programs target schools where classes average 80 students or more. The goal is to motivate teachers while giving students a chance to learn in smaller groups.

Double shifts: Schools are encouraged to adopt double shifts for teaching. Classes are split in half and class time is reduced to make it possible for teachers to teach two classes instead of one. In some cases additional staff will be hired.

Improving motivation: Teachers are offered guidance on how to improve their performance. Baseline measurements of student performance and teacher knowledge and skills are taken. School-level results are shared with the teaching staff, and concrete steps are suggested to improve classroom management and performance. Individual performance tips will be provided by text messaging over mobile phones. In addition, some teachers will receive in-kind rewards, such as radios or mobile phones, for improved performance.


To evaluate the interventions, about 200 overcrowded schools participating in the program will be divided into four treatment groups and a control group. The four treatment groups are divided as follows:

  1. Schools that are encouraged to adopt double shifts.
  2. Schools that will provide teachers with guidance for improving performance,
  3. Schools that are encouraged to adopt double shifts and whose teachers are provided with guidance to improve performance.
  4. Schools that receive both interventions and whose teachers are offered in-kind rewards for performance improvements.

Baseline and endline data at the end of the two-year intervention will be collected for the four treatment groups and the control group using student standardized tests scores and teacher evaluations. In addition, researchers will interview teachers, observe classrooms, and check on teacher and student attendance in four unannounced visits during the program. The Ministry of Education’s detailed operational budgets will be used to measure the cost-effectiveness of the interventions against the outcome data.

Policy Impact

This evaluation will provide evidence on potential low-cost policy responses for maintaining or improving the quality of education in increasingly crowded schools in Uganda and in other developing countries. In particular, it will compare the impact of measures addressing class size, low-cost teacher motivational approaches, and combinations of these.