"First, do no harm" is a good dictum for doctors, and may be one for policymakers as well. Even the best-intended policies can cause an unintended ripple of harm. A new study from a Tennessee think tank (the Tennessee Education Research Alliance or TERA) delves into one unintended consequence associated with federal and state accountability requirements: teacher reassignment.

Analyzing patterns in how schools assign teachers in Tennessee's elementary schools, researchers found that schools are reassigning their less effective upper elementary school teachers to grades where there are no tests. Since these early grades build foundational skills like literacy, such moves could cause long-lasting harm to students and also undercut school improvement efforts.

These findings are consistent with other research that has demonstrated similar "strategic" reassignment in other states. Their impact on student learning also may be exacerbated by the fact that teacher effectiveness generally suffers when teachers switch grades, even when performance may not be the reason why.

There are no easy solutions to this problem, but districts ought to consider certain guardrails, especially when it comes to more vulnerable student populations. Put simply, districts should evaluate teachers' effectiveness prior to reassigning them, and set limits on how often schools can reassign ineffective teachers to lower elementary grades.