The researchers went through a simulation exercise, building on prior findings about the impact that great teachers have on their students, the fraction of incoming teachers who turn out to be strong performers in the classroom, and the "signal-to-noise" ratio in a teacher's performance during her first couple of years (i.e., how hard it is to tell whether a teacher is bad or just unlucky).
Is the teacher bad or just unlucky? Not a single mention of systemic strengths and weaknesses, not a mention of how the system handles developmentally challenged or behaviorally challenged students, not a mention of the facilities. But is a teacher bad or just unlucky made the cut.
Depending on the definition of "unlucky," I wonder if whole swaths of results were rejected because those teachers were "unlucky" enough to work for a district that has no idea what it is doing.
And despite all those variances and obstacles not of their making, at least 20% of teachers ought to be retained. I guess those folks really are making a difference, holding their respective systems and schools together through expansive work weeks and constantly going the extra mile. If the bad teachers are the reason schools fail, good teachers must be the reason schools succeed.
Not so fast, my friend:
The cumulative benefit of attending a New York City charter school is sufficiently large as to almost erase the math performance gap between low-income kids in Harlem and those in affluent suburbs by the time kids get to the eighth grade. Better teachers are surely part (but not all) of the explanation for this success.
Surely. Better teachers are a part of charter school success. They play some role not yet quantified.
But. Not. All.
So, class, let us review: when a school is failing, you need to look to the teachers, of which 80% - according to this study - are failing the students and just collecting checks and benefits. We need to look no further for the schools that fail. BUT, when a school is successfull, teachers are surely a part, but only a part of that success.
Because the folks in charge should not be held accountable for failing schools, but they should be recognized for their role in creating successful schools, especially charters.