A friend of New York Times columnist David Brooks has completed a rigorous assessment of charter schools operated by the Children's Zone, the Harlem educational enterprise founded by Geoffrey Canada.

Canada tackled the problems of low student performance in one of the country's poorest urban centers with great success. And everyone is trying to figure out how he did it. Former City Schools Superintendent Manny Rivera met with Canada and tried to bring the concept of surround care to Rochester

Canada saw a need to create a safe external environment for children to encourage better learning. The phrase "surround care" was coined as a reference to seeing students holistically - including their health and safety.

Brooks and his colleagues attribute most of the success of the Children's Zone charter schools to highly structured teaching models under union-free management. Strict attention is paid to attitude and behavior.

Even more important, he says, is the "no excuses" mantra of Children's Zone educators. In other words, poverty is not an excuse for low performance; if children understand what is expected of them, they'll rise to the occasion.

Some of this is true, of course.

But the Harlem Children's Zone works for other reasons, too.

The charismatic Canada is a powerhouse of passion for his cause. He attracts investment.

Timing played a role, too; Harlem was in the early stages of a renaissance.

But this type of success is hard to duplicate without a Geoffrey Canada-like personality; someone with an ability to raise money.

We saw that with Rochester's Children Zone. Rivera managed to get some initial funding, but a long-term funding stream for the Rochester Children's Zone was going to be a challenge.

There's also a question about the student selection process with some charters, including Harlem Children's Zone. Critics argue that cherry-picking students, even poor students, improves the odds for success. Public schools must admit all students.

Charter schools may have a friend in President Obama, though he is not flush with cash at the moment.

Along with health care and energy, Obama sees the crisis with public education and how it is linked to the economy.

We need to know more about charter schools. We also need to know why some urban public schools succeed and others fail.

Columnist Brooks compares the miracle of charter schools to welfare reform for obvious political reasons. But many will agree with his call for reform because nothing short of a miracle is needed.