The city is pulling charter schools into the letter-grade game, and the privately run public schools have quickly jumped to the head of the class, claiming the top two spots in the city and raking in more A and B grades than traditional public schools.

Just 14 of the city’s 60 charter schools were graded this year, but city officials said that next year grades would go to all eligible charter schools.

Of the graded schools, only one received an F, while five earned As and six earned Bs. That means 79% of the graded charter schools got As and Bs, compared to 62% of the city’s traditional public schools.

Two “A”-graded middle schools, the Williamsburg Collegiate Charter School in Brooklyn and the KIPP Infinity Charter School in West Harlem, got the two highest grades in the city, when you look at the numeric scores that justify the letter grades.

“They clearly just knocked it out of the park,” the Department of Education’s executive director of charter schools, Michael Thomas Duffy, said. “It shows what is possible. I think that’s one of the best things that a charter can do, is say, ‘We can take these same students, and we can do amazing things with them.'”

The grades come weeks after Mayor Bloomberg handed letter grades to all the city’s traditional public schools, to a mixture of applause and grumbles. Though 75% of parents of school-age children told pollsters they approve of the grades, there were also some complaints about the formulas used to devise the grades.

The formula weights progress on test scores heavily, along with the results of a survey of parent, teacher, and student satisfaction. Charter schools’ grades were calculated by nearly the same formula, though they lacked satisfaction survey data and replaced that portion of the grade, which counted for 10%, with attendance figures.

Mr. Duffy yesterday said the city always intended to hand grades to the charter schools it authorizes, but the process took longer because charter schools, which are run privately, are not under the department’s direct purview, so data collection was more difficult. They were also limited to the schools that are overseen by the city rather than by the State University of New York, which also authorizes city charter schools.

Next year, SUNY has agreed to let its schools participate in the grades, Mr. Duffy said. Eventually the grades will even be factored into decisions about whether charter schools have met their five-year benchmarks, he said.

The executive director of the New York City Center for Charter School Excellence, James Merriman, said it was something of a question whether charter schools, which prize their autonomy, should really be saddled with grades given by the city.

He said ultimately schools welcomed the grades, and he said he does too.

“Schools grade kids, and so schools should receive grades themselves,” the superintendent of KIPP schools in New York City, David Levin, whose three eligible New York City schools all got A’s, said.

The director of external relations at the Achievement First charter schools, Lesley Esters Redwine, whose Crown Heights middle school received a B, said Achievement First welcomes the grade, even if it is lower than the network’s charter competitors.

Charter school skeptics often argue that the schools’ high performance is actually inflated by a “creaming” process, where schools are allowed to pick the most able students from the start.

Charter schools in New York follow a lottery application process; anyone can apply, but only those who apply can attend.

Mr. Levin said the students who come to KIPP look just like those at traditional public schools. At KIPP Infinity, he said, special education students make up about 11% of the total, compared to 10% citywide.

But he said KIPP takes its critics’ concerns seriously, and the organization is undergoing a five-year study to investigate the claim.
The principal of the Williamsburg Collegiate school, Julie Trott, yesterday said her school is so welcoming last year she recruited two applications in a shoe store.

Ms. Trott, who is 30 years old, named several factors to explain her school’s high marks: the support of the team at Uncommon Schools, which includes four professional headhunters; a hard-working staff that puts in extra hours at not much higher pay; and regular testing every six weeks so teachers can pinpoint where each student needs help.

“We just basically are super, super serious about academics and don’t play at all,” Ms. Trott said.

A professor of political science and education at Columbia Teachers College, Jeffrey Henig, said the grades for charter schools are interesting but not conclusive on charters’ quality.

He said his study of school grades issued to non-charter schools suggests schools get a boost if their students start out scoring low on tests, since grades give a strong weight to progress. If charter schools take students who performed poorly in the past, they might be performing well because of a similar phenomenon, Mr. Henig said.

“There might be a one year burst for kids when they come in,” he said. “It would be an open question whether that would be sustained as those kids progress year to year.”