Los Angeles has an unusually wide spread in the relative effectiveness of its teachers, according to an analysis released today by the Strategic Data Project, an initiative housed at the Center for Education Policy Research at Harvard University.
The study looks primarily at math teachers in the district who were teaching in grades 3-8 from the 2004-05 to 2010-11 school year, and uses a growth measure to arrive at the calculations.
Among the findings:
• The difference in performance between top- and bottom-performing elementary math teachers was one-quarter of a standard deviation, or nearly eight months of learning, a figure the report characterizes as larger than in other districts that have been studied.
• Teachers who entered the district through Teach for America or the district's Career Ladder program, which helps paraprofessionals obtain full teaching positions, were slightly better on average than other teachers in math, giving kids a boost of roughly one to two months of learning. But the career ladder teachers were much more likely to stay in the district than the TFAers.
• Extended substitutes in math were generally more effective than new hires, an interesting finding given the bad rap normally given to substitutes. The report notes that such teachers are often former district teachers and encourages more study of this population.
• Novice and early-career teachers were disproportionately assigned to lower-achieving students.
• Over his or her first five years in the district, the average math teacher improves enough to be able to give students the equivalent of three additional months of math instruction.
• Credentials generally were not linked to performance, but teachers with certification from the National Board of Professional Teaching Standards tended to outperform others by the equivalent of one to two months, though it's not clear whether those gains are a function of the certification process itself, or of the teachers who elect to become board-certified.
Perhaps the most important point to note is that the achievement gap between white students and students of color in the district is about 0.65 to 0.85 of a standard deviation. While none of the teacher effects studied were enough to close that gap on its own, some of them—like getting the very best elementary math teacher—appear large enough to make a dent in it.
Read the whole report here.