Very often, when using a chat tool where more than one participant is talking simultaneously, it is difficult to follow the conversation, read all the different messages and work out who is talking to whom about what. This problem has been dubbed "Chat Confusion." This article investigates this problem in debate sessions in an online university course. Chat Confusion has been singled out as the main limitation to using chat in educational activities. Confusion needs to be reduced for understanding to increase, making it easier to track what is being discussed during a learning activity. This study investigated the phenomena responsible for causing this confusion. A version of the Mediated Chat tool was developed for each problem identified and was subsequently tested in online courses. This article describes the Mediated Chat development process, the problems identified, and the results obtained from the case studies.