If you think that firing the bottom 5-10 percent of teachers every year would improve our education system, consider this:
Currently, around 8-9 percent of teachers leave the profession every year, and this will probably increase as baby boomers retire. Maintaining the deselection might place substantial strain on the labor pool (of course, there would be some overlap – teachers who would be fired under the proposal would have left anyway).
In particular, high-poverty and other hard-to-staff schools—which already have problems finding good new teachers—would have to replace even more teachers every year, while choosing from an ever-narrowing applicant pool (it seems that much of California is in trouble right now). The assumption that the quality of replacements would remain stable is rather unsafe, and the calculation hinges on it.
Moreover, you can bet that many teachers, faced with the annual possibility of being fired based on test scores alone, would be even more likely to switch to higher-performing, lower-poverty schools (and/or schools that didn’t have the layoff policy). This would create additional, disruptive churn, as well as exacerbate the shortage of highly-qualified teachers in poorer schools and districts.
When all is said, it’s conceivable that, taking the firings, attrition, and switching into account, the total annual mobility rate for all teachers could approach 25 percent, and it would be much higher in poorer school districts (making these students bear a disproportionate burden for this unintended consequence). It’s hard to imagine a public education system that could function effectively under those circumstances, let alone thrive.
Remember also that a widespread test-based firing policy would almost certainly change the “type” of person who chooses to pursue teaching (or, for that matter, chooses to remain). I find it hard to believe that any top-notch applicant would be attracted to a low-paying professionbecause of a systematic layoff policy (see here for an alternative view). There’s no way to know, but my guess is that the opposite is true. If so, the policy’s projected benefits would be further mitigated.
The simulation also assumes that all the dismissed teachers would leave the profession permanently. Again, this seems highly unlikely, especially if replacements are in short supply. Rather, I would speculate that a significant proportion of dismissed teachers would get jobs in other districts. In doing so, they would seriously dilute the policy’s effects, while also creating needless turnover for schools.