My stepmother is a principal at a public h.s. and was a teacher for 15yrs. She goes to a lot of conferences and reads a ton. One of the things she's shared with me was a study she read about. Unfortunately I do not recall the name of the study, or where it was published, but it showed that a good teacher can advance a child on average 1.5 grade levels in one year. But a bad teacher can slow a child down by 2 grade levels. As with many things in life, it takes a lot of good to overcome one bad.

~amy