In response to the increasing heterogeneity in Austria's vocational secondary and higher schools, the COoperative Open Learning (COOL) was introduced in 1996. The concept, based on Dalton Plan pedagogy, follows the idea of constructivist teaching-learning processes, which are primarily initiated through work assignments and are intended to lead to independent and cooperative learning. The author examines the extent to which this form of open teaching influences the cognitive and non-cognitive learning processes of students. To this end, a supply-utilization model was developed that describes the conditions for successful self-directed learning. Based on longitudinal data, multilevel analyses were conducted to examine the impact of open teaching on performance development in the subject of accounting and on the development of methodological competence. Furthermore, additional aspects were explored.