The best and worst teachers can be identified in their first two years in the classroom by value-added analysis, according to a working paper by University of Virginia and Stanford researchers. Teachers improve as they gain experience, however early effectiveness ratings predict how teachers will be evaluated after five years in the classroom, the study concluded.
Researchers tracked new fourth- and fifth-grade teachers in New York City, analyzing their students’ achievement-test results in math and English/language arts, as well as gender, ethnicity, home language, poverty, special education status, and absences and suspensions. Teachers’ value-added ratings — their ability to improve students’ achievement — in the first two years were compared with the next three years.
Overall, the teachers improved significantly in their first two years in their value-added score. While more than 36 percent of teachers were rated in the lowest of five levels of effectiveness at the start of their careers, only 12 percent were still rated in that same quintile by their third year of teaching.
However, when teachers at each initial level of effectiveness were tracked individually over time, their growth was much less significant. Compared with other teachers who started at the same time they did, teachers in the lowest 20 percent were still likely to be in the lowest 20 percent three to five years later.
Firing teachers in the lowest 10 percent in value-added effectiveness after two years would eliminate 30 percent of the least-effective group in five years, pointed out Tim R. Sass, an economics and public-policy research professor at Georgia State. Principals wouldn’t lose any teachers who’d eventually be rated in the top 10 percent.