Table 1.

Overview of the intervention components used in the ‘Snack Track School’ app

Behaviour change technique	App intervention components
Rewards	Credit system: in-game credits linked to the nutritional value of the chosen snack (a continuum from 0=unhealthy to 55=healthy), more points are given for healthy snacks
Goal setting	Personal goal selection every week
Active learning	Credit system Bonus system linked to the healthiness of their snacking pattern and selected goal Weekly in-game report that gives an overview of the eaten snacks and the received credits and bonuses
Advanced organizers	Credit system Weekly in-game report
Mere exposure	More exposure to healthy snacks as participants receive more credits/points for healthy snacks
Positive reinforcement	Credit system Bonus system Storylines and weekly competition/cooperation assignments linked to received credits
Monitoring	Snack track tool Weekly in-game report
Feedback	Bonus system Weekly in-game report