I was told in my earlier years that a teacher is one who imparts knowledge.
  If that definition is accurate, then all of us as human beings qualify as teachers. In fact, we all impart knowledge at one point or another in our lives. 
However, a professional teacher is one who is trained and assigned the job to impart knowledge in exchange for an income (my definition). 
I believe anyone who has chosen the profession to teach has an outstanding responsibility, regardless of the age group chosen to teach. There are indeed certain characteristics of a teacher which make them stand out from any other profession.