As before, effective teachers were spread more or less evenly throughout the district. But there were often large disparities among instructors who taught similar students in similar schools — even within the same schools. The differences among teachers were more than three times as great as those among schools.
It seems to me that at the school level there are a handful of possible outcomes of this value-added fad:
- We find, as above, that teacher quality is actually fairly evenly distributed -- thus it cannot be the source of the achievement gap.
- We find that teacher quality is unequally distributed with lower-poverty schools getting the best teachers. This cannot be resolved politically. Deadlock.
- VAM finds that the best teachers, are in higher poverty schools. This would be seen as a flaw in VAM.