Pop quiz! Try to solve this word problem. If students in Louisiana make more progress over time than almost any other state’s, does that mean Louisiana’s education policies are working or failing? What if I tell you that Louisiana, despite its impressive gains, still has a long way to go in terms of its students’ absolute performance? Now would you say that its policies are failing?

The right answer, of course, is that Louisiana’s education policies are succeeding. And indeed they are. A recent analysis by the Rand Corporation found that the state’s fourth graders made the greatest gains in reading on the latest National Assessment of Educational Progress; they were tied for first place in math gains. That’s a promising sign that Louisiana’s embrace of higher academic standards, tougher tests, and quality charter schools and school choice is paying off, and the state should stay the course. This rapid improvement should be a source of pride for the state’s policymakers. They inherited a dismally performing system; all they could do was adopt policies that would lead to big gains, mindful that reaching lofty targets would take time.

The same logic applies to educators. They have no control over the academic level of the students who enter their schools and classrooms; all they can do is to help them make as much progress as possible while in their care. So when evaluating schools, the fairest approach is to focus mostly on what they can control: “student growth” — or, in educationese, “value added” — rather than a student’s performance level at one point in time.

Thus the Louisiana Accountability Commission deserves kudos for proposing that the state tweak its A-F school accountability system to focus more on student growth than it has in the past. But instead of applauding the move, The Advocate’s editorial board, plus a gaggle of advocacy groups, have criticized it. “Over-emphasizing student progress,” the groups wrote, “is misleading to parents and the public about the performance of the school.”

Misleading parents and the public is of course worrying — but that’s precisely what the current system does. Consider KIPP New Orleans Leadership Academy, a K-8 charter school that gets a perfect 10 out of 10 for the progress its students are making from year to year. Its teachers can’t help it that many of its students come through its doors unprepared for kindergarten. What they can do is help those children make maximum gains every year, by teaching their hearts out, staying late, and pushing their pupils to work hard. These teachers deserve recognition and gratitude. The school deserves plaudits. Yet the current system gives it a mediocre C. Isn’t that misleading to parents and the public? Demoralizing to teachers and students?

If it were up to me, I’d give that school an A-Plus for its awesome learning gains, just as I’d give Louisiana’s policies an A-Plus for leading the nation in learning gains. If that’s too rosy, given how far the school’s students — and the state — still have to go, a B would be reasonable. (That’s probably what KIPP New Orleans Leadership Academy would get under the proposed system, as growth would still count for just a quarter of its overall grade.) What’s unreasonable is arguing that students’ learning gains should count hardly at all, which is how the present system works.

The Advocate and the concerned organizations are right that we have to keep our eyes on the prize — whether children will be prepared to succeed in postsecondary education and on the job. That’s why it’s essential that Louisiana continue to report honestly to parents about whether their own children are on track for that kind of success.

But evaluating schools is another matter. High-growth schools deserve high marks for excellence — which is exactly what they are demonstrating every day of the year.

Michael J. Petrilli is president of the Thomas B. Fordham Institute, a Washington, D.C.-based education policy think tank, and a research fellow at the conservative Hoover Institution.