Small, Dynamic Teams enable interactions and adaptation through close relationships and clear responsibilities. A team size of seven, plus or minus two maintains optimal channels of communication on the team, and minimizes the effect of an interaction penalty.
Organizing the project into small teams implies a low interaction penalty and can trigger this interaction. Allowing members to roll on or off the team allows dynamic team composition and enables adaptability to changing external conditions. When the project requires a larger team size, organizing the project into several smaller sub-teams working in parallel is a good compromise. The agile manager establishes clear roles and responsibilities to create team alignment and ensure accountability.