The granting of tenure typically occurs after K–12 teachers have worked three years in the classroom. In many places, that’s it, just time-in-harness. Thankfully, however, some states do require that teachers meet specific benchmarks relative to student test performance or classroom observation scores. One would imagine that the latter would be preferable, but a recent study out of Tennessee puts that notion to the test: Does lengthening the tenure process, coupled with a measure of minimum effectiveness, improve teacher performance? Tennessee’s approach to tenure provides a natural experiment by which to investigate that question.
The Volunteer State has had a tenure policy for its K–12 teachers since 1951, with longevity being the sole criterion for earning the job protections it affords. The state’s Race to the Top grant, awarded in 2010, created a new teacher evaluation framework, and the passage of Public Chapter No. 70 in early 2011 connected the framework to tenure eligibility. Specifically, to be eligible for tenure, teachers needed to have completed five years of teaching and to have earned annual levels of effectiveness (LOE) scores above the state-determined cutoff in both years 4 and 5. (The LOE is an average based on three measures: 50 percent for classroom observations, 35 percent for value-added performance, and 15 percent for student achievement.)
Teachers who missed the cutoff point (which equated to the bottom third in LOE performance) could continue on a probationary contract in year 6 and beyond, but they could earn tenure only after scoring greater than 4 out of 5 on their LOE in two consecutive years. (In practice, few teachers were let go for not performing well enough to get tenure, despite that intention at the start.) These changes went into effect at the start of the 2011–12 school year.
Harvard researcher Eric Taylor leverages this policy change to see how various elements of the evaluation and tenure process impacted a teacher’s job performance. He uses data from 2008–15, four years before and after the start of the new program in 2011–12. He includes only ELA and math teachers in grades 4–8 who are in years 1–7 of their employment, both because Tennessee has long had annual tests in those grades and because newer teachers are most likely to be motivated by the tenure incentive. He uses a difference-in-differences design to assess the effects on teachers hired in 2010 or 2011, relative to the announcement of the new tenure rules, implementation of the new performance measures, and other factors.
The comparison group were teachers hired in 2009 or earlier, prior to the 2012 evaluation reforms. The “treatment effect” is measured as the growth in performance between the first and second year (or second and third year) of a teacher’s career, but it is additional growth on top of the typical/predicted growth between those years that Taylor uses as the true impact of the new policy. (Typical growth is derived from the comparison group.)
His key finding is that teacher performance began improving before any rewards or consequences were in place. Teacher value-added scores increased by .05 of a standard deviation (SD) in anticipation of the new policy, with math and ELA teachers both improving—although math teachers improved more.
The linking of performance measures to earning tenure begins in year 4. However, little improvement appears in year 4 since so much improvement occurred earlier. Nearly two-thirds of teachers earn tenure after year 5 and their scores in year 6 no longer count for tenure, but their value-added gains persist and do not decline. In other words, teachers keep performing at higher levels even after earning tenure via the new scheme. Moreover, newly-tenured teachers improved a further .025 SD between years 5 and 6.
The non-tenured teachers (one-third) largely stayed in their jobs in year 6, showing that the new tenure rules did not increase or decrease typical attrition. Even though they didn’t (and probably never would) get tenure, teachers still didn’t leave on their own, nor were they forced out in any greater number than during the previous tenure scheme. That likely would not have been the case had districts been able to let go of low performers.
On balance, it seems that Tennessee’s efforts to improve teacher performance were beneficial for students. What would have made them even better? Getting rid of tenure entirely, as Florida, Kansas, North Carolina, and Wisconsin have done. As my favorite curmudgeon once said, “[S]hould teachers, often by the age of 25, obtain guaranteed lifetime employment in a school system on the basis of a few years of satisfactory evaluations? For that matter, should anyone get lifetime tenure in any job?”
Ok, I’ll answer his rhetorical question: No. A BIG, FAT no.
SOURCE: Eric Taylor, “Employee evaluation and skill investments: Evidence from public school teachers,” Annenberg Institute at Brown University (May 2024).
