Randomization and Masking
The randomization was stratified by grade and allocated to individuals at a ratio of 1:1. The randomization list was generated using R software, version 3.6 (R Group for Statistical Computing). To avoid stigmatization for being selected or not, children, parents, and teachers were educated on the purpose of the study and randomization. They were also informed of the right to withdraw at any time. Children and their guardians were aware of the study allocation due to the nature of the intervention. Outcome assessors and statisticians were masked.