Setting, Trial Design, and Sampling
The trial was registered with ClinicalTrials.gov, number NCT03893851 (registered on March 28, 2019), and our study protocol including power analysis based on (multivariate) ANOVAs (not accounting for potential cluster effects) has been published Flow diagram of the two-arm matched cluster-randomized controlled trial. Public primary schools were randomly selected from the six selected regions that ensured representation of the country geographically, economically, socially, and politically. First, two districts were randomly selected from the respective region. Only schools with more than 40 students per enrolment year in the selected districts, as obtained from the National Examination Council of Tanzania, were alphabetically listed in the selection list. One school was randomly drawn from the selection list (see Masath et al., 