Strengths and Limitations
One of the strengths of the present study is its design: we used a two-arm matched CRCT design, intent-to-treat analysis, a multi-informant approach, and a large student sample that was blinded regarding their school’s allocation. Additionally, the intervention and control groups showed comparable school setting-related characteristics at baseline, which further underlines that the detected effects can be attributed to the intervention. The stratified sampling approach considered the diverse geographic, economic, and social backgrounds of students and teachers at public primary schools in Tanzania. Furthermore, potential cluster effects were statistically accounted for by using the mixed model approach. The participation rate was very high and the dropout rate low. Of note is that teachers in the intervention and the control condition have dropped out at significantly different rates (However, there are some limitations to be mentioned. First, missing data is a common and an important problem in longitudinal studies, as it can lead to biases and false conclusions (Salazar et al., 