schmave
1) Past Performance (presumably, whether the teacher raised his students' test scores the year before, although it's not defined)
2) Whether or not the teacher majored in math
3) Whether or not the teacher participated in TFA
4) Whether or not the teacher has a Master's in Education
The best predictor is #1, which just means that the best predictor of whether a teacher is good at raising test scores is to see if they were good at that last year too. That doesn't seem very surprising to me.
Yes, the best teachers I had may have increased my standardized test scores some as a side effect, but it would be an insult to them if that's why I admired them so much as teachers.
Test prep can be done in a factory, but not education.
So, there is plenty of work to do to see that this problem stays solved.