Study design
In a pilot phase (winter term 2017/2018), students were asked to voluntarily participate in bPbL groups. Nineteen students from two bPbL groups and 29 students from three cPbL attended the pilot study, i.e. they filled in the questionnaires described below. The pilot phase was to check for technical feasibility of our approach, to validate the questionnaire (see below), and to check for feasibility of our guideline for semi-structured interviews. The main study was a randomised controlled trial. Thus, in the main study phase, 317 students were randomly allocated to 12 bPbL and 27 cPbL groups, respectively. Random numbers generated in Excel decided which PbL group the students participated in and thus whether this was a cPbL or a bPbL group. Since the study was also intended to investigate the feasibility of this blended PbL approach, and since it was unclear whether the students might be at a (perceived) disadvantage, we decided to use fewer bPbL groups than cPbL groups. While attendance of the PbL meetings was mandatory, filling in the questionnaire was voluntary. The final written exam was a summative exam, so most students took it at the end of the course.