Chair: A Chair, in the broadest terms, is there to moderate the panel. The session will begin when the Chair convenes the session at the start time by welcoming everyone. First, the Chair should remind everyone of the format: each presenter will be given up to 30 minutes for their paper presentation, then, after all of the papers have been read in that panel, the Discussant will be given an opportunity to offer brief comments and/or questions before opening the floor for questions and answers. After making this clear, the Chair should proceed by introducing the first speaker; simply give their name, school affiliation, and the title of their paper. Once they have finished reading their paper, there will be applause; announce the next speaker in the same fashion.
Chairs should bring a watch, paper, and pen because it is their responsibility for keeping time. If a speaker is getting close to their 30 minute time allotment, give them a "5 minute warning" by sliding a piece of paper indicating thusly to them. It may be necessary to ask them verbally to draw their talk to a close so that there is ample time for discussion. Once the final paper has been read, open up discussion by inviting the Discussant to respond to the papers. After the Discussant, if you have any comments or questions for the panelists, feel free to share them as well. Then allow for as much open dialogue as possible. It will be the Chair's responsibility to call on people who raise their hands, as the presenters should be able to focus on answering questions, etc. Thus a Chair will have to take the leadership role, otherwise it can get a bit confusing. Be sure to ask the questioner which panelist their question is for and ask that the questioner to speak loudly and clearly so that everyone in the room can hear their question. Also, in order that as many audience members as possible have an opportunity to join the dialogue, limit the amount of questions and time a single questioner has, unless no other audience members have questions.
Discussant: The Discussant is meant to start the conversation once the panelists have finished formally presenting their papers. Thus, during their presentations, you should take notes, writing out a couple of questions for each presenter. These questions might range from asking for clarification of a certain point they made to offering a possible counterargument. You might be able to fashion a question that pertains to both papers, or you might ask each panelist a question separately. Then, if there is strong audience participation, there is no need to ask any further questions; try and allow for free, creative, ad hoc questioning as much as possible. But if there is a lull in the question and answer period, in order to avoid any periods of awkward silence, the Discussant ought to ask another question or make a further comment.
Chair: If the session is near its end - say five minutes left - and there are no further questions or comments, the Chair should call the session to an end. Be certain not to run over the time limit, as we want to allow everyone sufficient time during breaks for refreshments, etc. At the very end, the Chair should ask for a final round of applause for the panelists and announce the starting time of the next session/activity.