Quality assurance
A number of data quality assurance activities were undertaken at the different stages of the study. Participants were enrolled in the trial after they have been well introduced to the trial objectives and the amount of time it could take to answer the questions. The participation was based completely on the willingness of the participants and their parents. Data were collected whenever they had free classes, at break time, before the day’s class begins or immediately following class ending, based on their preference. When the filled questionnaire was returned, correction for completeness, consistency and accuracy was done on the spot before the student left the room. There was an attempt to make pre- and post-test data collection contexts (timing and place) as similar as possible. Both the baseline and end-line data were entered into epi-info version 7.1 as a separate data set and exported to Stata 16.0. The two data sets were then merged using a unique but common code for both of the data sets. The principal investigators supervised the data collection. This report was prepared using the Consolidated Standards of Reporting Trials (CONSORT) guideline extension for cluster randomized trial [