Statistical analyses
REGRESSION
All statistical analyses were conducted with Stata V16.0 (StataCorp). Descriptive statistics at the school and student level were calculated for relevant variables by frequency counts and percentages. Bar charts were used to visually compare teacher feedback on the various teaching components and promotional materials, whilst a time-frequency graph was used to show actual water consumption as measured by the data loggers.Ordinal logistic regression modelling was used to estimate the marginal and joint effects of BI and CWS on the outcomes of weekly consumption of plain water and SSB. We controlled for correlation between baseline and follow-up using clustered standard errors at the student level. In doing so, our analysis avoided using a complete-case analysis approach, as students who completed only one of the two surveys were not excluded from the analysis. To control for confounding and ensure all models were parsimonious, a two-stage screening process was undertaken. Variables with a univariable For each analysis, unadjusted and adjusted OR with 95 % CI were calculated for all retained variables. The assumption of proportional hazards and model specification were assessed by the Brant test