One student of mine dominated her group by doing all the assignments way ahead of everyone else. She was so confident her answers were accepted without questions. As the work became more difficult, her work was increasingly less correct. By the end of the term others in her group had either excessive absences or had withdrawn. Groups with good leaders are the most productive groups.
Good leaders see to it that the work gets started and completed.
Good leaders see to it that all group members are involved in the group s work. All groups need students with some diversity in cultural backgrounds. In groups where everyone has a non-assertive personality it is likely no one will emerge as a leader. Students not meeting, students not caring about the work. When one or more of these problems exists, they usually decided to form a new group.