We implemented two different blended learning concepts using STACK. The aim was to enhance continuous learning activity of up to 1600 undergraduates in each of our courses right from the beginning of a term. In both scenarios, classroom exercises were partially replaced by voluntary e-learning tasks. In the first scenario, lecture hours were used to spend more time on difficult exercises in the classroom. In the second, lecture hours were reduced and bonus points for the final exam could be earned by submitting additional e-homework. E-homework with bonus points triggers active participation in the other (online and classroom) parts of the same course and therefore improves continuous learning.