Table 2.

Summary of design principles.

Devices - practicality/ease/comfort/aesthetics	Easy to fit
	Wearing two wristbands was acceptable
		Appear to be a standard fitness device (e.g., show time)
		Ability to distinguish left/right
		Longevity of battery and simplicity to charge
		Privacy/security of the device (summarize data into one-minute epochs, locked access)
		Synchronize data when possible (does not need mobile device continuously connected)
Smartphone application and game - incentives	Simple/fun game
		Synchronize data from bands and to server so that “points” can be earned towards game and that data can be viewed on application
		See own data
		Game as an incentive (cooperative but with a competitive edge; smartphone-friendly; longevity)
		Privacy (device locked, paired to device, access token can be revoked)
Protocol for proof-of-concept study	Participant age group broadened
		Buddy is optional
		Information card for school; ensure teachers are aware
Ethics and participant wellbeing	Privacy/security of the device (summarize data into one-minute epochs, locked access) – minimise what data is shared with the buddy
		Finding a buddy and not being left out.
		Young child having access to a smart phone (phone needs data access to sync – Internet safety education leaflet