One of the problems with these bonus programs is figuring out who the most effective teachers are and whether their effectiveness is portable. A teacher may dazzle in a middle-class school where students perform at grade level and parents jam open houses, but may fizzle in a classroom in a high-poverty area where many kids are behind and parents are too busy working two jobs to attend science fairs.

We are still not adept at separating out how much of student performance reflects socio-economics and family inputs and how much hinges on teachers and schools.

Consider the release Thursday of the Georgia Milestones scores, the state exams given each spring to elementary, middle and high school students and used to rate both schools and educators. In the five-county metro area, the top middle school for eighth-grade math was Dodgen in Cobb and the top elementary school for third-grade language arts was Lake Windward in Fulton. Both schools have 6 percent of students eligible for free and reduced-price lunch, the proxy for measuring low-income households.

When you go to the other end of the spectrum, the lowest-performing schools on this year’s Milestones, many have 90 percent or more of their students qualifying for free and reduced-price lunch.

At Banneker High School in south Fulton, nearly nine out of 10 students failed the state geometry exam, scoring below proficient, at the beginner or developing learner level. No student scored at the advanced level, according to the state data released last week. Its free and reduced-price lunch eligibility is 100 percent, according to the state Report Card. At Milton High at the other end of Fulton County – with 11 percent low-income students — 24 percent failed the End of Course geometry test. Nearly 30 percent scored at the highest level.

Would $20,000 persuade math teachers from Milton to move to Banneker where the lift to student proficiency would be far more arduous and frustrating? Even if they agreed to move — and most likely would not, given the distance and the challenges — could they be as successful with students arriving in geometry class in need of remediation?

As one teacher said, “It’s easy to look like you’re the best when your students are all on grade level and come to class every day. The better strategy is to grow the people you have on site and give them the supports they’ve been begging for for years.”