A teachers strike in the nation’s third-largest school district has prompted considerable discussion this week about the waning power of unions, along with some political tittering about President Barack Obama’s former chief of staff going nose-to-nose with organized labor.

But the strike, which pits Chicago Mayor Rahm Emanuel against a union representing more than 26,000 teachers, also puts a national spotlight on an important battle that’s being fought state-to-state, even school district by school district. That fight involves the role of testing in how teachers are evaluated and paid.

Chicago teachers are resisting efforts to place greater emphasis on students’ standardized test scores in teacher evaluations. It’s a position shared by educators and advocates across the country, including in Charlotte, and a movement to ban high-stakes testing has found some traction in scattered districts. But despite those efforts, half of U.S. states have agreed to launch teacher evaluation initiatives that take student achievement into account in exchange for federal Race to the Top program dollars or waivers from No Child Left Behind standards.

One such state is North Carolina, which is rolling out new year-end exams this year that include math and reading tests tied to more rigorous “common core” standards that dozens of states are adopting. North Carolina also is working on 90 new tests, known as “measures of student learning,” that will be used to evaluate teachers in subjects that don’t have year-end exams. That means that across the state, public school teachers could soon be evaluated in part on how their students perform on tests. We think that’s a good thing, with caveats.

In three years, when there’s a sufficient body of data from the new tests, student scores will be one of six areas where CMS teachers will be evaluated. It’s unclear at this point how those areas will be weighted; thus far, CMS officials say that the state plans to use a formula to calculate a “value added” rating that shows how much a teacher helped students master their material. Teachers who have a string of low ratings will lose their jobs.

We share teachers’ concerns that there are factors outside the classroom that affect how students perform on standardized tests, but that’s an argument for having test scores be one of several evaluation tools, not for abandoning high-stakes exams altogether. Those tests, done right, are a legitimate way to give principals additional insight into which teachers are performing well, and they better protect parents from having their children taught by the ones who aren’t.

The big question: Will North Carolina’s tests be done right? For starters, they need to call on students to use more of the thinking and analytical skills that common core advocates have touted.

One potential procedural snag: The Observer’s Ann Doss Helms reports that CMS officials are expecting to train teachers to score the questions on the exams that require written responses instead of multiple choice answers. But officials couldn’t say how the state would ensure comparable training and scoring in all counties.

But such is the uncertainty that comes with new initiatives. There’s sure to be more bumpiness, and yes, we share the fatigue of teachers and parents at this perpetual state of “rolling out” we seem to be in. Reforms are rarely easy, but with schools, they’re necessary. And testing, used smartly, can be a useful tool in helping our students and teachers improve.