Aim: In Italy, a handbook has been developed based on the principles of cooperative learning, life skills, self-effectiveness, and problem-solving at high school level. Early studies have shown the handbook's effectiveness. It has been hypothesized that the revised handbook could be more effective in middle schools.
Method: The study design is a "pre- and posttest" that compares the results obtained from 91 students of the high schools with those of the 38 students from middle schools. The assessment was made through "self-reporting" questionnaires of (a) learning skills including problem-solving and (b) perceived self-efficacy in managing emotions, dysfunctional beliefs, and unhealthy behaviours (i.e., drinking/smoking).
Results: Significant improvements were observed in both groups with the exceptions of perceived self-efficacy in managing emotions. The improvement of dysfunctional beliefs and the learning of problem-solving skills were better in middle schools.
Conclusion: The results confirm the authors' hypothesis that the use of this approach is much more promising in middle school.