Wake County's schools did pretty well for themselves last year. SAT scores were way up, advanced placement exams looked good and roughly 90 percent of schools made solid academic growth on state-mandated tests.

But the academic gains were uneven, class sizes have grown and the recession has eliminated entire courses in high schools.

So naturally, the issue dominating the upcoming school board election is student diversity.

To understand why, it helps to understand Wake's history. The current version of the school system was literally built upon the belief that diverse schools are better schools. It was called racial integration in 1976 when the Raleigh city schools merged with the county. The same was true in 1982 when magnet schools were created to attract white students to empty downtown seats.

By the late 1990s, most educators understood poverty mattered more than race. And poverty, of course, comes in all colors.

But something else happened during those years. The schools kept getting better -- and the rest of the country noticed.

Business leaders recruited heavily by emphasizing the quality of all the schools. The schools got the benefit of more middle-class families -- the backbone of any good system. And towns like Cary and Holly Springs exploded. It was boom town. It was wonderful. It was not diverse.

Study after study suggests poor students stand a better chance of succeeding academically in schools with a significant middle-class population.

Simply putting a poor student in a seat next to a middle-class student doesn't automatically raise that child's test scores. Creating schools with high concentrations of poverty, however, does produce a fairly uniform result - higher costs for test scores that are often worse.

Diversity guarantees something else. True neighborhood schools -- at least to the degree they can be achieved -- can't be promised. And that's the rub.

Many people attracted here by good schools believed their school would be located in their neighborhood and shared with their neighbors. While the vast majority of students do attend a school close to home, the fact that it can't be promised is unsettling.

So when it's time to reassign students -- a certainty in a district growing this fast - a policy that puts a poor kid from 10 miles away into a middle-class neighborhood is sure to be targeted.

But not everyone has shared in the growth yet. The percentage of poor students in some of Wake's eastern schools tops 50 percent. Growth there will be harder if entire schools start to tank.

And there is still the problem of how to improve the performance of poor kids regardless of where they attend class. It's a difficult dilemma. If providing an excellent education for everyone was easy, Wake would have licked the problem years ago.

Instead, it's been mostly a grinding, upward climb. So next summer, after the election hyperbole has faded, Wake's students will probably post another year of solid -- if uneven -- gains.

And the adults will still be arguing about diversity.