The active break program involves the presentation of video (4.5 min) with moderate-to-vigorous physical activities. These active breaks will be performed 6 times per day during 6 weeks.

This group of students will not be exposed to the intervention.

Active break program

Physical activity will be measured with waist-worn ActiGraph GT3X+ accelerometers for seven days. Physical activity intensities will be derived from the accelerometer counts. Evenson cut points will be used to classify counts into physical activity intensities. Physical activity will be classified as light, moderate-to-vigorous and total physical activity.

The Direct Behaviour Rating Scale will be used to measure on-task behavior at the individual level. This scale measures academically engaged, respectful and disruptive behavior. For each domain, the scale uses a per cent grading system in which 0% indicates 'never' while 100% indicates 'always'. At the group level, the Classroom Behaviour and Assets Survey will be used teachers who will be asked to indicate the proportion of the class displaying on-task behavior as defined by the individual behavior tool. Response options include: 0 (0 students), 1 (1-2 students), 2 (a few students), 3 (about ¼ of the class), 4 (about ½ of the class), 5 (about ¾ of the class), 6 (most of the class), and 7 (all of the class).

The Physical Activity Enjoyment Scale (PACES) will be used to measure enjoyment during the active breaks. Each of the 14 items of this instrument includes a Likert-type scale that ranges from 1 (Disagree a lot) to 5 (Agree a lot).