The use of acoustic 3D modelling software has become increasingly popular among acousticians. Some software developers offer introduction courses for starting users. However, there is a need for more advanced courses for experienced modellers. Such a course should not only consist of lectures with the scientific background of the model, but should also give room for sharing practical experience so one can learn from one another. In this context a master class on room acoustic prediction modelling has taken place in January 2010. A significant part of this master class consisted of a modelling workshop. By working on an assignment in small groups participants were stimulated to discuss ideas and exchange knowledge. The workshop was divided into four different parts, each part carefully tuned to the theoretical lectures in between. The workshop assignment was to compare predicted room acoustical parameters with measurement results concerning reverberation and speech intelligibility in an open plan office. Also an auralisation had to be made using multiple sound sources. The open plan office of the Laboratorium voor Akoestiek of Eindhoven University of Technology where the workshop took place served as an interesting modelling object. This room was interesting for educational reasons, since the participants were inside the room, as well as for acoustical reasons, because it consists of two coupled volumes, many details like furniture and a wide range of different materials. In this paper the assignment will be elucidated and the results will be presented. The response of the participants and the experience of the master showed that a workshop is an indispensible part of master classes in the field of room acoustics.