Seniority, in the modern reformy lexicon, is among the dirtiest words. Senior teachers are not only ineffective and greedy and never put interests of the children over their own, but they are in fact downright evil, a persistent drain on state and local economies and a threat to our national security! By contrast, “effectiveness” is good and since seniority and effectiveness are presumed entirely unassociated, the simple solution is to replace any reference to seniority in current education policies with measures of “effectiveness.”

If only it was so simple. This modern reformy mantra grossly misinterprets the relationship between seniority and effectiveness, presumes currently available measures of effectiveness to be more useful than they really are at sorting “good” from “bad” teachers, ignores that the proposed solutions have in many cases been found NOT to solve the supposed problem, and is oblivious to the broader literature on teacher labor markets, compensation and the quality of the teaching workforce.

Seniority and Effectiveness

Numerous studies over time have shown that as teachers reach somewhere around their 5th year, student achievement gains under those teachers begin to grow more slowly and to an extent level off.[1] These findings, to the extent we believe that these metrics of test score gain adequately represent teaching effectiveness, do not by any stretch of the imagination mean that more experienced teachers are less effective. Rather, their effectiveness increases from year to year level off. If they have indeed reached their optimal performance then it makes sense to continue to compensate senior teachers in order to retain them. A constant cycle of replacement costs money and costs in terms of lost effectiveness during the start-up years.