Abstract: At our university, the undergraduate program in Computer Science and Business Informatics (CSBI) faces a high student dropout rate especially during the first year of studies. One reason is the students' heterogeneous pre-university CS education, in particular concerning programming, due to inhomogeneous biographical backgrounds and different types of secondary schools. To tackle this knowledge-gap by levelling up those without or with little programming experience we have developed the massive open online course (MOOC) Programming with Processing. The MOOC comprises various learning activities and materials to study, exercise and self-assess basic programming concepts at individual learning speed using the programming environment Processing. The first course run comprised 6 chapters and has been implemented and evaluated with 577 prospective CSBI students. In this practice-based paper, we present the MOOC course design and the development, testing and implementation processes, the pedagogical background and we discuss our lessons learned so far.