At Hallandale High, for example, Eckhardt said there are about 250 students who live within the school’s attendance boundaries, but attend high school somewhere else. Thanks to this new A grade, Eckhardt said she was hopeful she could lure some of those kids back.

State education leaders were pleased with how Florida’s high schools fared overall, with the number of A schools rising and the number of D and F schools dropping. This year, 14 Florida schools received a D score, while three schools earned an F.

Still, Florida Commissioner of Education Pam Stewart warned: “You have to use caution when comparing 2011 to 2012.”

The reason comparisons are so difficult: Florida’s formula for grading schools often changes from year to year, with this year being no exception. In some ways, the grading method for high schools became more difficult — graduation rates were calculated using a stricter standard, for example — while in other ways the formula became simpler, as the state no longer factors in whether a majority of low-performing students showed learning gains.

Asked if this year’s formula is, overall, tougher or easier than last year, Stewart responded: “I really believe that that question would be too difficult to answer.”

For schools that struggled under this year’s formula, the state limited any negative grade change to one letter grade — from a B to a C, for example. Had that protection not been in place, the state acknowledged that three additional Florida schools would have earned F grades.

The constant change to the formula is one of many reasons why U.S. Rep. Frederica Wilson — a former member of the Florida Legislature — is harshly critical of Florida’s policy of grading schools.

“You cannot grade a school unless you have a consistent formula from year to year,” said Wilson, a Miami Democrat. “They have juggled the formulas around so that the schools can look rosy, so that they can continue the same malarkey.”

Another formula change this year was the inclusion of disabled students (some of whom are battling life-threatening illness) in school grades. Three of Miami-Dade’s educational centers that specialize in such students — Neva King Cooper, Robert Renick and Merrick educational centers — received an F grade. Similar schools in other parts of the state also struggled, though some school districts (including Broward) avoided getting a bad grade through a work-around option offered by the state.

In a nutshell, the state agreed to not grade those educational centers if districts would assign disabled students’ test scores to their neighborhood high school. Those scores would likely have a slightly negative impact on the neighborhood school (a school the child doesn’t actually attend) but the educational center would not have to worry about getting a failing school grade — which could imperil its ability to stay open.

Carvalho said Miami-Dade rejected the work-around “based on principle.”

“We believe that shifting the accountability for students to schools whose teachers never saw them or taught them is deeply flawed,” Carvalho said. “How can a child’s accountability be assigned to teachers and schools that they never attended?”

To see a specific school grade, go to schoolgrades.fldoe.org.