The following, list suggests some key responsibilities and qualities of a leader. You might want to brainstorm a list like this with your students.
Working democratically, consultatively and supportively, making sure that everyone participates and gets listened to.
Keeping a clear, unambiguous task focus and a sense of progress towards a common aim.
Organising, structuring and restructuring, as the task proceeds: forming subgroups, dividing up tasks, setting sub-aims, setting time limits, agreeing roles, etc.
Maintaining a happy, engaged, positive working atmosphere.
Pushing and nudging: encouraging people to think more laterally, feel more engaged, move forward and achieve even more than they believed they were capable of.
Dealing with dissent, obstacles and failures in open, creative and supportive ways.