Behaviour	CHAT Item	Criteria
Diet	How many portions of fruit and vegetables did you eat yesterday?	Agreement: If self-reported fruit and vegetable consumption aligns with those visually seen or if portion reported is 1 portion over or under estimation. Non-agreement: If none of self-reported portions are observed if all three or two meals are observed. Or if number of portions observed and recalled are more than 1 count difference, e.g., reported 5 when only observed eating 3 servings. Unable to align: If only one eating episode is observed then participant excluded.
Diet	What did you eat for breakfast? What did you have to eat for lunch?	Agreement: Can see participant eating/ preparing the meal that is self-reported. Non-agreement: If self-reported meal type does not match the observed breakfast or if report eating breakfast but it is not visually seen. Unable to align: If participant has not worn autographer during the given meal time.
Diet	What did you drink for breakfast? What did you have to drink for lunch?	Agreement: If a child self-reported drinking and this was observed in images. If the type of drink is identified, then this can be verified. Can clearly see the food being consumed is as the participant has self-reported. Non-agreement: If self-reported drink is not observed or vice versa, drink observed but not self-reported. Unable to align: If participant has not worn autographer for the morning or over the lunch time.
Physical activity	Before lessons started/after school how long did you spend doing sports or exercise?	Autographer Agreement: Self-report is within ±10 min of moderate physical activity derived from autographer annotations. Non-agreement: Self-report is greater than ±11 min of moderate physical activity derived from autographer annotations. Unable to align: If participant did not wear the autographer for greater than 30 min after school, they were excluded. Accelerometer Agreement: Self-reported duration is within ±10 min of time spent in MVPA. Non-agreement: Self-reported duration is greater than ±11 min of time spent in MVPA. Unable to align: If autographer was removed for >30 min after school.
Physical activity	How did you get to school yesterday morning?   How did you get home yesterday?	Autographer Agreement: Self-report mode aligns with visual observation. Non-agreement: Self-report does not align with visual observation Unable to align: If autographer was not worn during the journey.
		Acelerometer Agreement: Self-report mode aligns PA intensities engaged in during journey time derived from autographer images. Non-agreement: Self-report mode does not align with PA intensities engaged in during journey time derived from autographer images. Unable to align: If accelerometer was not worn during the journey.
Physical activity	Did you travel with an adult?	Agreement: Self-report aligns with visual observation during journey. Non-agreement: Self-report does not align with visual observation during journey. Unable to align: If devices were not worn during the journey.
Physical activity	What did you do for most of your morning break yesterday?         Apart from eating your food, what did you do for most of your lunchtime yesterday? What did you do for most of your afternoon break yesterday?	Autographer Agreement: Self-report intensity aligns with the most time spent in particular behaviour (standing, walking or moderate). Non-agreement: Self-report does not align with the most time spent in particular behaviour (standing, walking or moderate). Unable to align: If participant did not wear the autographer at time segment. Accelerometer Agreement: Self-report intensity aligns with the most time spent in a particular behaviour (sedentary, light or MVPA). Non-agreement: Self-report mode does not align with the most time spent in a particular behaviour (sedentary, light or MVPA). Unable to align: If participant did not wear the accelerometer at time segment.
Lifestyle	Before lessons started/after school, how long did you spend watching TV, playing computer games, using iPad or internet?	Agreement: Self-report is within ±10 min of observed screen time. Non-agreement: Self-report is greater than ±11 min of observed screen time Unable to align: If autographer was not worn majority of the before-school or after school period (If only worn for 30 min, then removed from analysis).
Lifestyle	Before lessons started/ after school, how long did you spend doing homework/reading?	Agreement: Self-report aligns with amount of time observed on camera, over- or underestimating time by 15 min and below. Non-agreement: Self-report does not align with time observed on camera, over- or underestimating by greater than 15 min. Unable to align: If autographer was not worn majority of the before-school or after school period (If only worn for 30 min, then removed from analysis).
Lifestyle	What time did you get up yesterday? What time did you go to sleep yesterday?	Agreement: If the self-report is within ± 30 min and below of the accelerometer and autographer-derived placement/removal time. Non-agreement: If the self-report is above ± 31 min of the accelerometer and autographer-derived placement/removal time. Unable to align: If either the autographer or accelerometer was clearly placed or removed hours after or before the get up or sleep time.
Lifestyle	How many times did you brush your teeth yesterday?	Agreement: If some self-reported episode of brushing teeth is observed in autographer images and/or recorded in information booklet. Allow for overestimation of brushing episode by 1, e.g., twice reported but only 1 observation. Non-agreement: No observations of brushing teeth observed or self-reported removal of autographer for using bathroom in a.m./p.m. Unable to align: No observations of brushing teeth observed with the autographer or no records in log booklet of removal to use bathroom in a.m./p.m.