Every classroom, whether filled with young students or old, needs a leader.  Ocassionally, you will find a classroom where one of the students has taken over as leader and the teacher no longer has any influence, and may even be tied to her desk.  Some people are born leaders.  They think clearly with vision and can easily implement programs and activities to fulfill that vision.  An article in the Washington Post describes the leadership of one man who conducts orchestras for a living.  Throughout the years, he has learned how to be a leader who is effective in communicating a vision and in coaching capable musicians to follow him.  In music, if the director doesn't have a clear vision as to how the music should sound, the ensemble, no matter how talented or skilled, will sound sloppy, unprofessional, and not unified.  However, the director who has a clear vision and can clearly and effectively communicate that to the musicians is able to produce a beautiful, cohesive melody. The same is true for the classroom.  Leaders, and in this case teachers, ought to be able to clearly articulate what it is they desire the students to learn.  Students ought to understand what it is they are expected to learn and, in turn, be able to produce.  Teachers who lack vision and clarity will also lack the results and understanding they are expected to produce.