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Anger and aggressive behaviour are part of everyday school-life and have been reported to be negatively associated with student well-being and academic performance. School-based interventions, developed to target anger and aggressive behaviour, are scarce. One such Danish intervention, the so-called Mini-Diamond, has been developed and implemented in several Danish municipalities. The aim of the current study was to evaluate the potential effects of the Mini-Diamond on student well-being in a controlled trial. Outcome measures included aspects of child-and parentrated student well-being, including school connectedness, learning self-efficacy, and bullying. All children in grades 0-2 in Rødovre (intervention) and Herlev (control) municipalities participated and filled out the same questionnaires. No effects of the Mini-Diamond intervention were found on any of the outcomes. Potential reasons for this are discussed, including the possibility that there is no effect of the Mini-Diamond intervention on well-being, together with limitations and implications of the current study.

Purpose Physical activity (PA) is an important factor contributing to general health. PA declines rapidly during tween years (9–12 years) when children’s social world changes. School playgrounds can contribute substantially to children’s PA, but little is known about how to motivate tweens to use school playgrounds. Using the three basic psychological needs (autonomy, competence, and relatedness) proposed by the Self-Determination Theory, this qualitative study aimed to investigate how school playgrounds can support tweens’ needs. Methods Tweens (n = 56) participated in focus group go-along interviews in their school playground. Results We found that tweens needed a variety of play possibilities (autonomy) that challenged their skills (competence) as well as areas to retract and be with friends (relatedness). Conclusion This research highlights the importance of incorporating tweens’ perspectives in playground design to attract and retain them in play and PA in school playgrounds.

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