Maggie's Farm

The majority of children/students, perhaps 60% or so learn an adequate amount from school such that their life is more or less successful. They do this with or without good teachers or good schools. They were preordained to be mediocre to average. About 25% or so of the children/students fail to learn enough to be moderately successful in life. Some will still manage to live a normal or near normal life. In most cases a good teacher or a bad teacher wouldn't make any/much difference and neither would a good school vs a bad school. They were preordained to fail or at least be sub-average.
The 15% or so that is left do in fact benefit from having good teachers and good schools. They will do well in life even if they do not get a "good" education but they can do so much more if they have good teachers and a quality education. That 15% are the students that teachers and schools can positively impact. The students that will go on to excel and maybe change the world. Do not let the other 85% of students dishearten you. With few exceptions you cannot change their most probable outcome.