By Emily Cohen and Priya Varghese

When the National Council on Teacher Quality asked Miami-Dade County Public Schools how good their teachers are, they didn’t know. An ignorance of the most fundamental information describing their most important employees was among several troubling findings in our recent study, “Teacher Quality Roadmap: Improving Policies and Practices in the Miami-Dade County Public Schools.”

In the nation's fourth largest school district, where 70 percent of students live in poverty and only one-third of fourth graders are proficient in mathematics and reading, teacher quality deserves far more attention. While Miami performs better than most urban district's on the National Assessment on Education Performance, known as the Nation's Report Card, it still has a long way to go.

Research shows that teacher quality is the single most important school-controlled variable that influences student achievement. And having a series of highly effective teachers throughout elementary school can substantially offset the disadvantages typically resulting from a low socio-economic background. For example, a recent study by Harvard and Columbia economists found, not surprisingly, that elementary- and middle-school teachers who help raise their students’ standardized-test scores, affect their students’ lives beyond academics, including lower teenage-pregnancy rates and greater college matriculation and adult earnings,

Using teacher evaluations as a tool to drive teacher quality reform would be a good first step for Miami. Teacher evaluations can serve as a tool to provide teachers feedback for what they need to improve, and also as a tool to help guide administrators when making decisions about staffing, professional development and compensation.

But when only 10 teachers out of a workforce of more than 20,000 were identified as underperforming in the 2010-2011 school year, it is clear that evaluations play little role in shaping district practice. Miami's rate for dismissing poor performing teachers is the lowest NCTQ has seen, though few districts in the United States have done a stellar job making teacher performance central to their reform efforts. For example, last school year, Springfield, Massachusetts fired 10 teachers out of a workforce of 2,100 and Los Angeles fired 280 of 29,000 teachers.

When Miami administrators were asked about these figures, they said they believed in the potential of every teacher – an admirable show of support and willingness to cultivate their educators. However, the district’s first priority should be to support student learning. That means a commitment to putting only the most talented teachers in classrooms, and making hard and sometimes uncomfortable decisions about adults.

Of course, the solution isn't to fire its way to a better school system. Miami needs also to raise up its most talented teachers. Give them more money, more strategically, to show that results, not just effort, are valued, and to encourage its best to stay and to lead in the district.

But on that front too, much improvement is needed. Currently, Miami reserves 70 percent of raises for teachers with at least 20 years of experience. Yet research shows that experience is a poor predictor of teacher performance. In fact, the effects of teaching experience level off after a teacher has taught for 5 years. In other words, on average a teacher is no more effective in her 20th year of teaching than she was in her fifth year of teaching. That's not to say that experience doesn't hold any value, but its effects on student learning are minimal.

For ways to improve and enhance the efforts already underway in Miami, our report points to Harrison County, Colorado, which recently revamped its teacher evaluation as a first step in systemic reforms. Harrison administrators, teachers and union leaders sat down to rethink the entire structure of teacher policies—soup to nuts, from staffing, to evaluation, to compensation. They defined an objective standard of performance for every single grade level and subject area, including subjects not tested in state mandated exams, that would signify what effective teaching looks like.

Harrison teachers are no longer paid according to how many years they have taught or how many degrees they have, but rather their impact on student learning, which is most objectively measured by growth on standardized tests. Harrison County leaders understand that dangling a $500 bonus as a way to reward teacher performance will not change teacher behavior. In the first year of Harrison’s new performance pay structure the district saw modest student achievement gains in most grades, and significant growth at the high school level. Perhaps most striking is that 25 percent of the teacher workforce left, the majority of who were not rated proficient.

Harrison is just one example that Miami can learn from. And many of the challenges before Miami require contractual or legislative changes, such as changing the structure of the salary schedule, but most simply require better practices on the part of the district. Practices like collecting data on teacher performance and using that data to inform staffing, professional development and compensation decisions would be an important first step.

Our work is the easy part. The challenge now rests with the community to keep the pressure for reform alive. It's the least that Miami's 350,000 students deserve.

The National Council on Teacher Quality, a nonprofit research and policy organization, recently studied the teacher policies in Miami-Dade schools. This is the eighth school district we’ve placed under the proverbial microscope in an effort to illuminate ways in which urban school districts can improve the quality of their teachers, and ultimately student achievement.