Recently, the institutionalized transformation of frontal instruction classrooms into active learning spaces to foster the concept of (inter-)active learning has gained increasing attention. To investigate the impact of elements of active learning on learning reception of students in an advanced small sized MSc STEM course (<25 students), a traditional instructor teaching style class was transformed to flipped-classroom teaching. Before and after each lecture, anonymized evaluation Likert items from the students were recorded. Thus, both teaching styles for every given lecture were covered equally. In both classrooms, some didactic and methodological elements were kept constant, while others were changed when flipped-classroom took over semester midterm. Qualitative and quantitative results indicated that the flipped-classroom format generated greater learning effects as well as classroom enjoyment, fostered students' self-regulated learning, enhanced group interaction, stimulated group activity and guaranteed a more synergistic learning behavior.