Discussions in an open chat room take place in real time, which means that everyone who wants to engage in the conversation must be present at the same moment. As a result, they can be more difficult to organise than forum conversations, and they’re also more difficult to monitor because the debates and responses happen so quickly.
Because of this, I prefer that you utilise forums with your students to conduct class discussions as opposed to an open chat room but if you do need to have a real time discussion in a chat room then the links below will allow you to set this up.