During the winter semester 2008/09, the Institute of Sports Science at the Goethe University in Frankfurt (Germany), conducted and evaluated a seminar for sports students called, "Good Practice in Physical Education". This novel teaching format was designed to link didactical skill-acquisition, in terms of situated learning, to the acquisition of theoretical knowledge, which should enhance the professional core competences of future PE teachers. In addition, this pilot seminar was designed to evaluate the usefulness of a blended-learning-teaching-approach, i.e. online learning combined with face-to-face learning, compared to a conventional attendance format. In both the seminar formats students worked together in constant small groups (3-4 persons). The blended-learning-groups (a total of 70 students) had 4 attendance and 9 online sessions, whereas the attendance groups (60 students) had 14 attendance sessions only. In order to make the learning progress between the groups comparable, at the beginning of the seminar the students were allocated as to the results of a baseline test assessing their knowledge about PE. The same test was conducted afterwards to measure the gain in knowledge with regard to the content of the lectures (for details see Prohl & Groben, 2010). Prior knowledge is expected to be a predictor of knowledge gain (among others McNamara & Kintsch, 1996; Renkl, 1996). For this reason, each treatment-group (blended-learning vs. attendance seminar) was subdivided into two sub-groups as to their performance in the baseline test ("high" vs. "low" level of prior knowledge; median-split). The differences in the gain of knowledge (dependent variable) between the treatment groups (independent variable A = IV A) and the sub-groups (independent variable B = IV B) were tested by means of multivariate analysis of variance (2x2 factorial design). In general the results show main effects for IV A (Treatment, p < .001) and IV B (prior knowledge, p < .003) as well as their interaction (p < .001). Detailed analyses reveal that in the blended-learning-seminar both sub-groups ("high" as well as "low" prior knowledge) significantly gained knowledge (p < .01). The performance gap between both sub-groups remained unchanged in the final test. In the attendance seminar, the students with "low" prior knowledge significantly increased their level of knowledge as well (p < .01). The "high"-sub-group, however, could not significantly raise their level of knowledge. Consequently, in the final test both sub-groups within the attendance format did no longer differ as to their proficiency. It can be concluded that the blended-learning concept used in the study offers good prospects for students to increase their knowledge, irrespective of their prior level of knowledge. This is in clear contrast to traditional teaching methods, as was confirmed by the results achieved in the attendance seminar. The beneficial effect of the blended-learning approach may be explained by the multimedia-based presentation of the learning content, which seems to activate learners with different prior knowledge to a similar extent and supports their knowledge gain in a more effective way.