This paper presents our experiences and the challenges identified in transforming traditional lecture-based modules at a university into problem-based blended learning within a social constructivist approach. Our experiment was, among other factors, motivated by an urgent need to meet new curriculum requirements by reducing the lecturing time in a graduate course on the subject of human-computer interaction. The results indicate that it is possible successfully to transform traditional modules into problem-based blended learning using a social constructivist approach, and moreover reduce lecturing time, support repetition and support educational differentiation. (Contains 6 figures.)