This exploratory case study was conducted in two upper secondary schools in Finland and Bulgaria. The aim of the study was to investigate how to apply trialogical design principles could be used to improve students' knowledge work competence, and teachers' re-structured obligatory courses following pedagogical design principles for knowledge creation practices. The courses were organised in the form of students' collaborative inquiry and project work. The research questions focused on the implementation of the design principles, students' self-assessed learning of knowledge work competencies and the experiences of students and teachers. The main data consisted of students' self-evaluation answers to a pre-questionnaire (N = 76) and a post-questionnaire N = 52), and teachers' (N = 4) plans and interviews. The results showed that students' experiences were positive, but they also found shortcomings in their knowledge work competences. The teachers were also satisfied with the experiences, but they found problems in teachers' collaborative planning at the end of the process (in Finland) and in organising student teamwork and in reporting the contributions (in Bulgaria). The set of design principles was useful as a collaborative guidance tool for the teachers' planning, and in these two cases, the form of an inquiry learning and project work. However, the teachers need practical guidelines to implement the trialogical design principles.