‘Blended learning’ and ‘Flipped Classroom’ as methods to acquire 21st century competences in heterogeneous mass courses

University lectures are facing higher quantities of students showing increasingly heterogeneous knowledge, interest and intellectual capabilities. To prepare those student groups for a changing, interconnected world, basic knowledge teaching is not sufficient any more. Instead, to let them acquire 21st century skills, e.g. strong communication and collaboration skills, expertise in technology, innovative and creative thinking skills, it is necessary to change the methods of teaching. Blended learning and Flipped classroom are concepts that can be combined to achieve these goals. The questions the paper addresses are: 1.) Do these concepts provide benefits when dealing with student groups that are strongly heterogeneous in knowledge, personality, culture, background? And 2.) How effective are these concepts, and which factors cause or prevent success?The research team, consisting of real estate subject lecturers and instructional learning design experts, set up an introductory class of business administration in a blended learning format and used this situation as a “real life experimental” study. During the study, 'big data' was collected and analyzed, operationalizing up to 250 students’ online behavior, their learning time slots as well as intermediary test results and direct feedback. The study was complemented by longitudinal surveys regarding the students’ motivation, workload sentiment, expectations, knowledge and other dimensions Also, a comprehensive evaluation survey was analyzed quantitatively as well as qualitatively.Survey results showed a large variance of the appreciation of the learning concepts which can be explained by several reasons. However, the workload sentiment was a major issue. Rather minor changes are sufficient to adress this problem, while the general concepts of blended learning and flipped classroom can be kept as effective learning methods. Yet, for fully assessing the learning success regarding 21st century skills, further empirical studies are necessary.The study provides recommendations of what works and what was not effective in a blended learning/flipped classroom course, e.g. how an incentive system can be designed to engage students in a constant learning process and increase interaction during the semester. The originality/value of the study is its focus on large, heterogeneous groups and its design as an experimental real-life study combining the collection of big data with quantitative and qualitative methods.