Esther Mertens

12 | Chapter 1 I evaluated this type of school-based interventions by means of a Randomized Controlled Trial (RCT) and a meta-analysis. I conducted the RCT to gain a detailed understanding of one specific intervention, Rock and Water (R&W; Ykema, 2002; 2018) – with a focus on prevocational students – and conducted the meta-analysis to increase insights in these interventions in general. More specifically, through the RCT and the meta-analysis I examined 1) the effectiveness of universal school-based interventions, 2) whether heterogeneity in the context and in the student population affected intervention effects, and 3) working mechanisms of universal school-based interventions. In addition, using both research approaches enabled me to discuss findings concerning one specific universal school-based intervention, as well as to relate these intervention specific findings to general findings of school-based interventions. Rock and Water R&W (Ykema, 2002; 2018) is a 2-year universal school-based intervention aiming to improve competencies and to prevent the development of problems in the intra- and interpersonal domain. The intervention is based on the “Rock & Water house” (see Figure 1). The R&W house consists of five levels representing the five modules of the intervention: Safety, assertiveness, social skills, the inner compass, and solidarity/ spirituality. In these modules, R&W teaches students how to feel safe, and how to prevent and deal with violence (i.e., safety), how to deal with difficult situations without losing self-control (i.e., assertiveness), how to have discussions with people who have different opinions, how to set and respect boundaries, and how to understand and use non-verbal communication (i.e., social skills). Students learn to value their own intuition and preferences, and to make choices based on their intuition (i.e., the inner compass), and increase insight in themselves and others as they are all connected with each other (i.e., solidarity/spirituality). The foundation of the house consists of the three pillars of self-control, self-reflection, and self-esteem. Closely related to these pillars is emotional self-regulation, a potentially fourth pillar. The R&W house theory states that students need to improve their self-control, self-reflection, self-esteem, and emotional self-regulation to be able to develop themselves within the modules of the intervention. The R&W intervention lessons are provided by teachers, mostly physical education teachers, during physical education classes. These teachers complete the 3-days basic R&W training course to become certified R&W trainers. Optionally, the rest of the school staff can follow an introduction training course of R&W during which the basic principles of the intervention are introduced. School staff learns how to apply the intervention principles during regular classes (e.g., math class) and how to support the R&W trainers within their school. In the manual, the role of the R&W trainer is explicitly described with a specific focus on the responsibility of the trainer