First, what did the study find? If we take the study's most conservative estimates for all eight high school subjects (7 math and science subjects, plus English I, and comparing North Carolina TFA teachers with non-TFA teachers in the same school )- the Teach for America advantage is .064 standard deviations, while teachers with 3-5 years experience provide an advantage of .024 standard deviations (compared to those with <3 yrs experience), teachers with 6-10 years of experience offer a .015 gain, and those with 11 or more years of experience offer a gain of .007 standard deviations.
The authors concluded that "the Teach for America effect, at least in the grades and subjects investigated, exceeds the impact of additional years of experience, implying that TFA teachers are more effective than experienced secondary school teachers….programs like TFA that focus on recruiting and selecting academically talented recent college graduates and placing them in schools serving disadvantaged students can help reduce the achievement gap, even if teachers stay in teaching only a few years.”
But small is small. I’m all for Teach for America as a stopgap, but the achievement gap claim is fanciful thinking. Why? By comparison, the black-white gap in NAEP math achievement in grade 12 is approximately 1 standard deviation (and is likely larger because many black students have left by grade 12). An advantage of .04 standard deviations over teachers with 3-5 years experience in the same school is not going to significantly close the achievement gap. This is not an advantage over teachers in the nearest suburb or the best schools in the city that don’t staff Teach for America teachers, and is hardly a convincing rationale to permanently staff tough schools with a revolving corps of academically talented 2-year teachers.
So my primary disagreement with this study stems from its conclusion, “policy makers should focus more on issues of teacher selection, and less on issues of teacher retention, if the concern is the performance of disadvantaged secondary school students especially in math and science.” For this to be true, we must assume that a school is simply an amalgam of pods in which teachers teach, such that a teacher’s decision to leave is independent of other teachers’ future efficacy. In other words, the authors presuppose that teacher turnover has no effect on the school as an organization, and that teacher quality is solely an individual attribute, rather than the joint product of individuals and organizations. (And what do we make of the tiny effects of experience? Is it possible that the most talented math and science teachers left to pursue more lucrative opportunities?)
It’s nearly impossible to build a stable school community and an ethos of sustained change in the face of regular turnover. Herein we have the classic chicken and egg problem in education: how do we create places where good teachers want to work - a key component of which is a stable professional community – if we can’t get strong teachers to stay? Programs like Teach for America are a fine band-aid, but they are hardly a solution.