Teaching is pragmatic: its effectiveness is often judged by results. If the students learn, the teaching is successful; if they don't, it is not. So the facts we must face are: there are people who simply cannot teach; and some of them refuse to acknowledge the fact. Some of those teachers without ability, know their limitations and leave the profession, generally those who survived were those who could teach and those willing to improve their skills.
A body of literature (Shulman,1987; Grossman, Wilson, & Shulman,1989; Ball, & McDiarmid, 1990; Cochran, 1993) has informed us that among the basic criteria for a teacher are: knowledge of the subject, and ability to impart it. You must know your subject well enough to teach it to impact learning. It is the unique ability of some teachers to impart their knowledge not only to the bright and disciplined students but to all including “the unteachables” that this paper is premised on.