Serious games are seen to hold potential to facilitate workplace learning in a more dynamic and flexible way. This article describes an empirical study into the feasibility of an online collaboration game that facilitates teachers-in-training to deal with classroom management dilemmas. A script to support these students in carrying out such practical tasks, independent of teacher intervention and in collaboration with peers, was designed and worked out in both a face-to-face and an online version of a "mastership" game. After assigning and discussing practical dilemmas during a small group play session, solutions are worked out individually in the form of small advisory reports, and assessed by both teachers and peers (co-players in the group). Learning effects were measured and satisfaction was questioned for 9 players that played the online version and 10 players that played the face-to-face version of the game. Results show that the collaboration of students on classroom dilemmas can indeed be successfully facilitated by this script, and that learning results do not differ for both versions. The latter holds potential for offering online and more flexible ways of workplace learning. Especially, students playing the online version reported needs for simpler structure and clearer task instruction. The optimal level of structure in collaboration scripts, therefore, appears an issue for further study.