Blinding
This is an open-label trial because it is impossible to mask the students when the intervention starts (baseline). Moreover, given that the first author of this manuscript is the research leader of the project, she will coordinate the field work and will act as one of the assessors based on her training on the assessment of the outcomes and intervention and thus will not be able to remain blinded from the study subjects. Since all the 18 assessments across time will be filmed after the agreement and reliability were checked by two assessors, the teachers will not be blinded on which phase of the intervention the students are assigned. However, the two assessors will code the outcomes independently to establish interobserver agreement on the coded observations.