A good policy is meaningless unless it’s carried out.

Michigan’s teacher evaluation system aims to equip schools to identify and retain high-quality instructors while encouraging ineffective teachers to find another line of work.

But school districts have not implemented it.

Providing effective teachers is the most important thing schools can do to boost student achievement. Lawmakers reformed state tenure law in 2011 with an evaluation system that tied tenure decisions to teacher effectiveness and enhanced school leaders’ staffing authority. This session’s House Bill 4354 would take away that authority and let ineffective teachers remain in the classroom.

The evaluation system has changed since 2011. The latest change took effect in the 2018-19 school year: The requirement that one-quarter of a teacher’s rating reflect student test scores was increased to 40%. Standardized test data allow school officials to assess a teacher’s impact on student growth.

Michigan schools statewide instead rated 99% of teachers “highly effective” or “effective” in the last three years. That happened as Michigan’s students scored record declines in achievement on the M-STEP test. That discrepancy between teacher ratings and student test data represents a failure to implement the evaluation policy.

When teachers are not evaluated on their performance, student achievement stalls. The evaluation system should give teachers feedback necessary for professional development. There’s little room for improvement, though, when schools declare 99% of teachers effective. They are passing on the opportunity to improve student outcomes.

This is not the first time failing to implement education policies has scuttled efforts to improve student outcomes.

State law required districts, starting with the 2019-20 year, to hold back third-graders who were one grade level behind in reading. Districts used the exceptions allowed in the law to promote to fourth grade the majority of retention-eligible third-graders. The law is no more. Legislators and the governor scrapped it earlier this year. Had the law stayed in effect and been enforced, students could have had better teachers, learned more, and been on the path to a better future.

Tennessee shows how a teacher evaluation system should work.

The Volunteer State’s system took effect in the 2011-12 school year, rating teachers on classroom observation metrics (50%) and student growth and achievement data (50%). A Vanderbilt University Study confirms that the Tennessee law improved student achievement.

Tennessee’s average fourth-grade reading score on the National Assessment of Educational Progress increased five points by 2013 — an increase no other state surpassed. Its eighth-grade reading score increased by a record six points. That growth was faster than in comparable districts in other states. Tennessee achieved its record growth by implementing a teacher evaluation system that focuses on two specific outcomes: teacher retention and teacher development.

Tennessee’s reforms resulted in more high-performing teachers and fewer low-performing ones. Strategic personnel decisions by school officials were not the only reason. A significant number of low-performing teachers chose to leave. As for the most effective teachers, they reported higher job satisfaction, which motivated them to stay.

Tennessee’s success in implementing its robust evaluation system helped the teachers who stayed become more effective. They received in-depth feedback from school officials who observed their classroom instruction, identified strengths, and recommended areas for growth. The more effective schools used more frequent observations performed by different evaluators, with an initial observation early in the school year.

Unlike their counterparts in Michigan, they did not rate every teacher the same.

Tennessee teachers were also more likely to stay in schools with highly rated principals. The state helped by investing in programs that helped principals become better leaders.

Tennessee has assessed the policy’s effectiveness and adjusted its practices. The percentage of teachers who see value in the system continues to grow. About three out of four teachers believe it improves their instruction and student achievement — more than double the portion who did when the law went into effect.

The lesson here for lawmakers is that it takes time to adopt and implement a successful policy. Creating a comprehensive evaluation system is the first step. A steadfast commitment to effective implementation and assessment is essential to success.

Michigan has failed to implement its teacher evaluation system, but it’s never too late to change course and get to work improving student outcomes.

Molly Macek is the director of education policy for the Mackinac Center for Public Policy.