N.C. Senate leader Phil Berger didn’t spend much time on education last week in his preview of the upcoming legislative session, but the Eden Republican provided a new clue about how his party will pursue the delicate issue of how we reward and dismiss our teachers.

Berger pointed to a landmark Colorado law, passed in 2010 and signed by a Democratic governor, as a potential model of teacher tenure and evaluation. The law forces teachers to earn tenure through performance, and it can rescind tenure if a teacher is ineffective over a period of time. That’s an improvement over what N.C. Republicans proposed last year – eliminating tenure altogether for a system of awarding teachers one- to four-year contracts. That plan died in committee.

Currently, most N.C. public school teachers are eligible for tenure after at least four years on the job. Once they achieve that career status, they can’t be fired except for proper cause. Critics here and across the country say that tenured teachers are rarely fired, no matter how poorly they might do in the classroom. States have tried to confront the politically thorny issue for years, and the Colorado law was seen as a breakthrough by many education reformers.

The law, which was introduced by Republicans and opposed by the state’s largest teachers union, requires that teachers have annual evaluations based at least 50 percent on student growth, measured in part by test scores. Teachers who receive three straight positive evaluations are eligible for tenure, which guarantees an appeals process before a dismissal. Tenure can be rescinded, however, if a teacher is rated “ineffective” for two straight years.

Education reformers hailed the law for its promise in identifying ineffective teachers and weeding out those that continued to perform poorly. N.C. lawmakers should pursue reform with the same goals, but with caveats:

First, the tests used for student and teacher evaluation must be done right. North Carolina is rolling out new year-end exams that include math and reading tests tied to more rigorous “common core” standards that dozens of states have adopted. CMS officials say that the state plans to use a “value added” rating that shows how much a teacher helped students master their material.

We think student testing is one legitimate way to measure teacher effectiveness, but it will take a few years, perhaps more, for the state to develop a sufficient body of data while working out kinks in testing and scoring. No tenure law should begin before the testing system is ready.

Also, any evaluation should combine those test results with assessments from peers and principals, who understand best the challenges teachers face in their classrooms and schools. If teachers struggle, they should have access to a professional support system that offers the opportunity for improvement before dismissal.

All of which takes money, but N.C. lawmakers shouldn’t be looking for a cheap education fix. North Carolina needs a tenure and evaluation structure that not only holds poorly performing teachers accountable, but also develops and rewards those whom we’d love to have standing before our children.