A strong trend to use collaborative systems in teaching can be observed. Often first experience is gained by conducting seminars or lectures with existing tools, e.g., using the MBone [7]. These tests generally find that the support of existing, mainly generic tools is not adequate for Tele-Teaching. While some projects directly address learning aspects, [4] these tend to be limited in scalability, mainly addressing smaller groups. Our approach is to develop a general framework and basic components, which can be used in a variety of scenarios. Currently the two main scenarios are a discussion group consisting of few (about 10) participants with equal rights, and a lecture scenario with more participants (up to 100) and a lecturer in control. For these scenarios, not only aspects of session control are relevant, but as well methods to provide feedback to the lecturer about the current session. This is achieved through a combination of visualization methods customized for the selected scenario. The session control uses a graphical representation of a room typically used in the specified scenario in order to provide feedback and to allow ease of use. The control marks tools currently in use allowing the lecturer and students to easily identify and participate in the corresponding media representation (e.g., audio and video). A special feedback tool allows rating, and can be used to gain feedback from the students about the received video and audio quality, the speed of presentation or any other resource one wants a rating on. These visualization measures combined with the floor control provided by MACS allow conducting a lecture in an efficient manner.