Esther Mertens

| 77 Role Personality in School-Based Intervention Table 1 Descriptives of Adolescents’ and Parents’ Demographics per Condition Light Standard Plus Control Differences at T1 F /χ 2 p η 2 partial /φ Demographics adolescents (n) 373 303 249 374 Age, M ( SD ) 12.33 (.57) 12.38 (.66) 12.34 (.60) 12.47 (.64) 3.89 .009 .009 Boys, n (%) 170 (48%) 161 (56%) 131 (55%) 199 (57%) 7.38 .061 .077 Western background, n (%) 291 (82%) 115 (43%) 211 (91%) 198 (59%) 182.01 <.001 .392 Demographics parents (n) 178 66 107 110 Age, M ( SD ) 43.11 (5.66) 41.82 (5.45) 43.85 (5.14) 43.39 (6.30) 1.82 .143 .012 Mothers, n (%) 155 (87%) 55 (83%) 84 (79%) 88 (80%) 4.30 .230 .097 Conditions R&W. The theory of R&W is based on the ‘R&W house’. This house consists of five levels that together represent the intra- and interpersonal domains. R&W theorizes that adolescents can develop themselves within the intra- and interpersonal domains by improving the foundation of the house (i.e., self-control, self-reflection, and self- esteem) and, closely related to that foundation, emotional self-regulation. R&W uses the symbolic principles of ‘rock’ and ‘water’ to indicate a continuum ranging from an uncompromising attitude to resist peer pressure (i.e., rock) to a flexible attitude open to the opinions, thoughts, and feelings of others (i.e., water). The intervention uses a unique combination of a physical approach and the more common psychological approach, i.e., a psychophysical approach. Through play and exercises adolescents increase their strength, learn how to make contact with others, and explore, respect, and set own and other’s boundaries. During the lessons, trainers create a safe and trusting environment in which there is respect for each other, there is room to make mistakes, and adolescents work together. Adolescents participate in physical exercises and games, reflect on the exercises, share their thoughts with each other, and address how to use the learned skills in their daily lives. The R&W intervention is a 2-year manualized program of which the first year consists of 14 lessons and the second year of 8 lessons. Each R&W lesson lasts 90 minutes and is weekly implemented during physical education classes. R&W trainers were teachers that successfully completed the 3-day training course to become certified R&W trainers. Most teachers were physical education teachers due to the physical nature of the exercises during the lessons (see the study protocol for more information about the intervention Mertens et al., 2018). Intervention Fidelity. Fidelity to the intervention manual was measured with questionnaires completed by R&W trainers and with observations conducted by R&W experts. R&W trainers reported that in general they could complete the lessons (65%), 4