It's attracted less attention than the gold-plated 2004 Mathematica study of Teach For America, but the National Bureau of Economic Research is out with a major study comparing the teaching effectiveness of alternate route teachers with teachers from traditional routes. While both sides of the teacher certification debate may cherry pick findings, the most appropriate response by all ought to be a dose of humble pie.
The study tracked some 65,000 New York City teachers of grades 4 through 8 through their first five years of teaching. In the first year, alt route teachers do not perform as well as traditionally certified teachers, most notably at the elementary school level and in reading. However, alt route teachers prove to be fast learners, able to make up lost ground and occasionally even capable of surpassing traditionally certified teachers by as early as their second year, but consistently by the third. By the third year, fellows in The New Teacher Project--a crew as sharp as TFAers, but who are older and likely to stay about as long as traditional teachers--are producing learning gains in middle school language arts and math that leave their traditional counterparts in the dust.
What are the policy implications here? As a guiding principle, secondary schools may be the best place for teachers coming from alternate route programs, reserving elementary assignments for teachers who have gone through a formal program--if such teachers are available (though in many instances they are not). But the real problem here is retention, and there are few solutions in sight. While the gap in effectiveness between training pathways narrows relatively quickly, the percentage of teachers who stay long enough to make up for those early deficits makes it almost impossible for schools to build strong faculties; this holds true for teachers from all routes, but not surprisingly, TFA teachers leave at the highest rate.