Hypothesis: the performance gap between good teachers and great teachers is as hard to quantify and as elusive to define as the performance gap between good pro

Hypothesis: the performance gap between good teachers and great teachers is as hard to quantify and as elusive to define as the performance gap between good programmers and great programmers. We all know that some programmers are 10x more effective than other programmers. What we don't know is why. I suspect the same is true of teachers. Otherwise, ++ for your comment about teachers having to follow scripts. The best programs aren't scripted, and the modern "money" solution (not necessarily supported by teachers or teachers' unions, by the by) is to tightly tie down the curriculum so that teachers have minimal impact on the delivery. Teacher friends who have taught in England have said that it's to the point of "it's November 4th, so we must be doing Triangles"; every student is supposed to be learning exactly the same thing on the same day. Nice in theory, but it doesn't work.