Recent research on school size suggests that student results tend to be lower in large primary schools than in small schools, but at the secondary level the results are mixed. The research also indicates that disadvantaged students tend to do better in smaller schools. Large schools also tend to have poorer social outcomes and lower parental involvement.
The research is reviewed in a recent study published by the European Expert Network on Economics of Education. The study reviews the available empirical evidence on the effects of school size and school consolidations on important outcomes such as student performance, inequality, attendance rates and parental involvement. The review focuses on studies that use sophisticated statistical analysis that attempt to determine causal links between school size and student achievement.
The study notes that the majority of sophisticated studies on the effect of school size focus on secondary schools and that there are very few on primary school size. It concludes from its review of primary school studies that:
The existing evidence suggests that there is a negative relationship between school size and academic performance at the primary school level. [p.22]
It concludes that the evidence is mixed for secondary schools. It notes that many studies are unable to establish causal links and are correlational in nature, which means that their findings should be interpreted cautiously.
There are education benefits and costs associated with school size. Large schools are potentially more diverse in terms of courses, teachers and peers. Diversity generally means more flexibility, for example, a more diverse peer composition allows schools to organize peer groups in specific ways that can enhance learning. Large schools make it easier to provide a wide range of courses for students and have teachers that are specialized in a particular subject. On the other hand, smaller schools may have a higher quality of social interactions and students may feel more connected to the school and this can lead to higher achievement.
The study found that there is no consensus on optimal school size and that it is dependent on a variety of factors and circumstances:
…there seems to be a consensus in the literature that schools should be neither ‘too big’ nor ‘too small’. Optimal school size is context-dependent and is likely to vary with country, region, degree of urbanization, level of education, student composition, student background to mention a few. [p.36]
Decisions about school size may also have more far-reaching consequences. Studies show that school size also affects other factors such as attendance, parental involvement and youth violence. Here the evidence is fairly conclusive:
Most of the existing evidence suggests adverse effects of school size on attendance rates, dropout rates and social outcomes. Particularly, the evidence suggests that larger schools are associated with lower parental involvement, less connectedness and more youth violence. [p.5]
In particular, studies have found that students in larger schools are more likely to be alienated from the other students and the teachers leading to frustration and eventually violent behaviour.
Overall, the available evidence suggests that larger schools are associated with less favourable social outcomes. [p.27]
School size is particularly important for disadvantaged children. Several studies find that larger schools harm disadvantaged students, but some find the opposite. One major US study found that inequality increases with school size and that there is greater equity in small schools because student socio-economic background has less impact on learning.
The study also reviewed research on the effects of school consolidation. Like school size, school consolidations can affect a variety of outcomes, including academic achievement, equity, attendance, school quality and peer composition. However, there are relatively few studies that look at causal links between school consolidation and different student outcomes and most focus on primary schools.
The effects of school consolidation on student achievement vary considerably for students displaced from schools and those in receiving schools. Generally, displaced students are more adversely affected by school consolidations than receiving students and the effects are more severe for disadvantaged students. However, the effects diminish over time and are reduced if students are transferred to higher achieving schools.
While most studies focus on the effect of school consolidation on student achievement, the review notes that there are other issues to be considered in assessing school consolidation. In particular, studies tend to ignore the effects on costs making it hard to evaluate the entire policy of school consolidation. Furthermore, school closings often have detrimental effects on the surrounding neighbourhood in terms of population flight, reduced housing values among others.
The report concludes that it is important for policymakers to take all the potential benefits and costs of changing school size into account. As a brief on the report states:
…..it is extremely important for school policy to balance the costs and benefits of school consolidations and school size. [p.2]
Larger school size may bring economies of size but these cost reductions can be offset by other costs. For example, the review states:
While it seems obvious that all costs must be taken into account, a simple thing such as the transportation costs incurred by students is often not included in analyses of the costs of changing school size. [p.35]
Changes in costs also need to be assessed against the impacts on education achievement and social outcomes. While the effect of school size on student achievement is very important, changes to school size, whether through new schools or school consolidation, need to consider a range of other potential outcomes as well. These include attendance in school, long-term educational success, student engagement, youth violence and parental involvement.
The study says that school size considerations are especially important in areas with a large percentage of disadvantaged students.
There is considerable evidence that students who are generally considered disadvantaged, for example students with low socio-economic status, language-minority status, low parental education level etc., are more affected by changes in school size than other students. [p.36]
It says that if a goal of school policy is to reduce inequality in school outcomes, it is important to assess the impact of school size on the distribution of student achievement. However, the relationship between school size and achievement is context-dependent and in some circumstances increasing school size may increase inequality but may reduce it in others. The study concludes that this underlies the need for high quality research on the effects of school size for different groups of students.