# **Introduction**

Despite substantial investments in infrastructure and teachers, many low-income countries still struggle with large class sizes in primary school, particularly in lower grades. The typical primary school in Sub-Saharan Africa has more than 30 pupils per class, but average sizes rise to above 50 in countries including the Democratic Republic of Congo, Tanzania and Chad (Bashir et al., 2018). In Malawi, the context for this study, class sizes are particularly severe with a typical school having more than 125 students to a class (ibid.). These poor conditions stem from the failure of national public education systems to keep up with rapid growth in school enrollments, the result of rapid population growth and rising enrollment rates over more than two decades since the introduction of free primary education by the majority of low-income countries in the 1990s (ibid.).

These poor conditions contribute to low rates of learning in lower grades. In Malawi, fewer than 25 percent of students in Grade 2 achieve minimum proficiency levels in reading according to the Early Grade Reading Assessment (EGRA) conducted by the United States Agency for International Development (USAID) (USAID, 2013). These poor levels of learning in early grades contribute to high rates of repetition, further exacerbating large class sizes, a case of ‘early grade bulge’ (Bashir et al., 2018). In the case of Malawi, repetition rates are typically above 25 percent in lower grades (Ministry of Education, 2022). Faced with these poor conditions, many students simply drop out. Fewer than three-quarters of remain in school until Grade 5 in a number of countries in Sub-Saharan Africa, including Uganda, Burkina Faso, and Mozambique (World Bank, b). In Malawi, around one in four students drop out prior to Grade 5 (Ministry of Education, 2022).

Large class sizes may prove detrimental to learning by reducing the level of attention received from teachers by each student, reducing students’ ability to ask and answer questions and seek guidance, and reducing the likelihood that teachers engage in time-intensive teaching tasks such as marking homework. In Malawi, evidence from the Malawi Longitudinal Schools Survey (see section ) suggests that, while primary school teachers are as likely as those in neighboring countries to correct mistakes and give positive reinforcement, they are substantially less likely to set and mark homework and to be available to support students after class, activities which increase in time commitment as a result of large class sizes (Asim and Casley Gera, 2024).

In addition to overall poor conditions in lower primary, many low-income countries have wide variations in conditions between schools, with poorer and more remote districts and sub-district areas typically having larger class sizes than wealthier districts and those closer to capital cities, particularly as a result of inefficiencies in the distribution of teachers (Mulkeen, 2010; Bashir et al., 2018). These inequitable conditions are associated with inequities in learning outcomes, with the least well-equipped districts and schools typically having lower learning outcomes. Evidence from cross-sectional data derived from a range of primary level standardized tests suggests that ‘raising the floor’ on test scores by improving the performance of the lowest-performing students and schools is likely to be the most cost-effective way for low-income countries to raise overall learning levels in the short to medium term (Crouch and Rolleston, 2017). In Tanzania, a recent set of reforms targeted to seven disadvan2