Just a dogs body; it is her job to pause the discussion from time to time to recap and agree on the positions reached so far. The leader does more then simply keeping it going; for example,she must ensure that everybody speaks and is heard. Brilliant teachers spend time on these roles, preferably by creating role cards for all members of the group which define their responsibilities. Even members with no additional job have a role card which defines the whole business of offering views, offering evidence, listening to counter-arguments, considering how to respond, moveing towards compromise, and so on.