NCT03817047.

Methods	Type of trial: efficacy Allocation: cluster‐randomised Intervention model: parallel assignment Masking: none (open‐label)
Participants	Estimated number of schools:  − Estimated number of students: 2045 Inclusion criteria (schools): − Exclusion criteria (schools): − Inclusion criteria (students): enrolled in Grade 9 Exclusion criteria (students): −
Interventions	Intervention 1: physical activity learning including 60 minutes of physical education in addition to ordinary PE lessons, 30 minutes of physical activity learning, and 30 minutes of physical activity a week to stimulate mastery, joy, and well‐being  Intervention 2: don't worry ‐ be happy, including physical education (60 minutes) and physical activity (60 minutes) as self‐organised activity groups of at least 3 students developed according to activity preferences Comparators: current practice
Outcomes	Primary outcome: physical activity  Secondary outcomes: time spent in MVPA, time spent sedentary, sedentary behaviour, upper limb strength, explosive strength in the lower body, abdominal muscle endurance, cardiorespiratory fitness, academic performance in reading, academic performance in numeracy, overall psychosocial problems and strengths, subjective health and well‐being, self‐evaluation of competence or adequacy, anxiety and depression, learning environment, school environment Other outcomes: BMI, waist circumference, satisfaction with psychological needs, emotional responses to physical education, eagerness to join physical education
Reason for awaiting classification	Recorded as completed in clinical trials registry, but no results published
Stated aim of study	Quote: "this study evaluates the effect of 120 minutes extra of physical education (PE) or physical activity (PA) on adolescents' physical health, mental health, academic performance and learning environment. This is a cluster‐randomised controlled trial with three arms, where the participants in two of the groups will have different models of increased PE/PA during the school week, whereas the participants in the third arm is the control group including current practice"
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