Table 2.

Description of the co-creation group and development and implementation of each school-specific intervention.

Description	School 1	School 2	School 3
General information	Technical and vocational education (Grades 7–12) All girls from one class from Grade 10 were invited to participate in data collection and co-creation group (14 girls in total)	Technical and vocational education (Grades 7–12) All girls from Grade 10 were invited to participate in data collection and co-creation group (8 classes in total; 103 pupils, 89 girls)	Part-time vocational education (≥15 years); the school deals with a lot of absenteeism and drop-out of pupils All girls from the entire school were invited to participate in data collection and co-creation group
Co-creation group	8 girls from one class Mean (standard deviation) age: 15.9 (0.7) years	13 girls from three different classes Mean (standard deviation) age: 16.1 (0.6) years	Initially 4 girls joined the co-creation group, but only 2 girls continued with the co-creation group (1 girl dropped out of school, 1 girl was pregnant and was mostly absent) Mean (standard deviation) age: 17.2 (0.0) years
Developed intervention	4 sport sessions at school during lunch break for girls only 4 different sports that are usually not covered in physical education (Zumba, hiphop dance, kickbox on music, workout with exercises on music) Using flyers and posters to announce the sessions to all girls from Grades 9–12	Facebook page with pictures and movies of exercises to do at home, healthy recipes, tips to be active, etc. One fitness activity for all pupils from Grade 10 (boys and girls), organised during school hours All pupils that took part in the fitness activity, received a bottle of water, an apple and a flyer with the link to the Facebook page	Walk to a park nearby during lunch break with a healthy lunch and the possibility to do a sports activity in the park (e.g., frisbee, soccer); all pupils (boys and girls) were invited to join and all participating pupils were invited to wear a pedometer during the activity to record the amount of steps The pupil with the most steps during the walk received an incentive Developing a teacher manual with tips to increase the activity levels of pupils PowerPoint presentation to all pupils and teachers of the school to encourage them to participate
Implementation of the intervention	Session 1 (Zumba): 9 participants (including 4 girls from the co-creation group and 5 girls from other classes/grades) Session 2 (Hiphop dance): 11 participants (including 3 girls from the co-creation group and 8 girls from other classes/grades) Session 3 (Kickbox on music): 11 participants (including 3 girls from the co-creation group and 8 girls from other classes/grades) Session 4 (Workout): 14 participants (including 3 girls from the co-creation group and 11 girls from other classes/grades)	Grade 10 was divided into 4 groups; 2 groups each went to a fitness center during the morning school hours and 2 groups each went to a fitness center during the afternoon school hours Every group was supervised by at least two school teachers All pupils from Grade 10 were subscribed to the fitness activity (103); but there are no official records how many pupils were actually present Both the girls and the researcher had access to post something on the Facebook page, but most posts were placed by the researcher and only few posts were placed by the girls	13 pupils participated in the lunch walk (including the 2 girls from the co-creation group) One of the girls from the co-creation group had the highest amount of steps (6005 steps) and received a small incentive