Esther Mertens

98 | Chapter 5 own preferences and choices, and to increase self-insight. This theoretical house is built on the three pillars of self-control, self-reflection, and self-esteem. According to the theory, strengthening students’ skills concerning these pillars enables students to develop themselves within the broader domains of the R&W house (see for more information about the intervention Mertens, Deković, Van Londen, & Reitz, 2018). R&W lessons were provided by teachers, mostly physical education teachers, who have followed the 3-day training course to become a certified R&W trainer. The rest of the teaching staff at the school received a 3-day training course to learn how they can support the R&W trainers and how to implement R&W during their regular classes. Students received 14weekly lessons of 90minutes during a four months period. The lessons were provided during physical education due to the physical nature of R&W as it combines a physical approach with a psychological approach, i.e., a psychophysical approach. That is, students learn through play and exercises how to make (physical) contact with others, and explore, respect, and set own and other’s boundaries. Each lesson is described in the manual and includes physical exercises, reflection, a moment of sharing thoughts with each other, and an exercise to strengthen the transfer of the learned skills to students’ daily life. Control. Students from the three schools in the control condition received care as usual. In one school this entailed a mentor students can go to with problems, a project week about ‘being different’ and an anti-bullying protocol. Another school had an anti-bullying coordinator and assigned a personal coach to each student with whom the student had regular meetings for advice and discussing the student’s wellbeing. The third school also had an anti-bullying coordinator and a mentor students could to go to. Measurements Perceived classroompeer context. Levels of comfort, cohesion, and conflict in the class were measured with three subscales of the ClassroomPeer Context questionnaire (Boor-Klip et al., 2016). The subscale Comfort assesses the level to which students feel at ease around their classmates (e.g., “In this class I can be myself.”), Cohesion assesses unity and inclusiveness among classmates (e.g., “In this class children like each other.”), and Conflict assesses students’ negative social exchanges in the classroom (e.g., “In this class children fight with each other.”). Each subscale contained 4 items answered on a 5-point Likert-type scale (1 =  totally not true , 5 =  completely true ). Cronbach’s α was for Comfort .71 and .84 for T1 and T2, respectively, for Conflict .83 and .88, and for Cohesion .44 and .62. Experienced victimization was assessed with 1 item of the global measures of the Olweus Bully/Victim Questionnaire (Solberg & Olweus, 2003): “How often have you been bullied at school in the past twomonths?”. This itemwas preceded by a definition of bullying. Frequency was indicated on a 5-point scale (1 = never , 5 = multiple times a week ).