NEW YORK – President Barack Obama created a grant program to copy his block-by-block approach to ending poverty. The British government praised his charter schools as a model. And a documentary opening across the country revolves around him: Geoffrey Canada, the magnetic Harlem Children’s Zoneleader with strong ideas about how U.S. education should be fixed.

Last week, Canada was in England, addressing Prime Minister David Cameron and members of his Conservative Party about improving schools.

But back home and out of the spotlight, Canada and his charter schools have struggled with the same difficulties faced by other urban schools, even as they outspend them. After a rocky start several years ago typical of many new schools, Canada’s two charter schools, featured as unqualified successes in the new documentary "Waiting for ‘Superman,"’ again hit choppy waters this summer, when New York state made its exams harder to pass.

A drop-off occurred, in spite of private donations that keep class sizes small, allow for an extended school day and an 11-month school year, and offer students incentives for good performance like trips to the Galapagos Islands or Disney World.

The parent organization of the schools, the Harlem Children’s Zone, enjoys substantial largess, much of it from Wall Street. While its cradle-to-college approach, which seeks to break the cycle of poverty for all 10,000 children in a 97-block zone of Harlem, may be breathtaking in scope, the jury is still out on its overall impact. And its cost – around $16,000 per student in the classroom each year, as well as thousands of dollars in out-of-class spending – has raised questions about its utility as a nationwide model.

Canada, 58, who began putting his ideas into practice on a single block in the mid-1990s, does not apologize for the cost of his model, saying his goals are wider than just fixing a school or two. His hope is to prove that if money is spent in a concentrated way to give poor children the things middle-class children take for granted – like high-quality schooling, a safe neighborhood, parents who read to them, and good medical care – they will not pass on the patterns of poverty to another generation.

"You could, in theory, figure out a less costly way of working with a small number of kids, and providing them with an education," Canada said. "But that is not what we are attempting to do. We are attempting to save a community and its kids all at the same time."

Few would deny that a middle-class renaissance is under way in the sections of Harlem where Canada and the Harlem Children’s Zone have focused their efforts. All children who live in the zone have access to many of its services, including after-school programs, asthma care, precollege advice and adult classes for expectant parents, called Baby College. The organization has placed young teaching assistants, known as peacemakers, in many of the elementary school classrooms in the area and poured money into organizing block associations, helping tenants buy buildings from the city, and refurbishing parks and playgrounds.

By linking services, the program aims to improve on early childhood programs like Head Start, whose impact has been shown to evaporate as children age.

Amid the facades of new condominiums that signal gentrification, however, deep poverty remains. So does low student performance in most of the neighborhood’s public schools, despite modest gains over the past decade and a growing number of better-performing charter schools, a development Canada helped pioneer.

Last month, the Obama administration awarded $10 million in grants to 21 neighborhood groups around the country to help them plan their own versions of the Harlem Children’s Zone, and the president is seeking $210 million for next year, although appropriations committees in the Senate and the House have earmarked only $20 million and $60 million, respectively.

But there has been some criticism. Grover J. Whitehurst, a co-author of a Brookings Institution analysis of the zone, said there was still too little evidence that its approach, of linking social services to promote student achievement, justified an investment of federal education dollars, and urged that a more rigorous study be conducted.

"My quarrel is not with an effort in Harlem funded largely by philanthropy; it’s with the federal approach to scaling this up," Whitehurst said. "It just doesn’t rise to the level of evidence the president and the secretary of education said they were going to apply in determining their investments."

In awarding the grants, Education Secretary Arne Duncan emphasized, the government hoped neighborhoods would coordinate and stretch their existing services, while asking the private sector to step up and match financing.

"The cost is going to vary community to community," Duncan said, "but we think this is an absolute investment."

In 2009, the Harlem Children’s Zone had assets of nearly $200 million, and the project’s operating budget this year is $84 million, two-thirds of it from private donations. Last month, the Goldman Sachs Foundation pledged $20 million toward constructing an additional school building. With two billionaires, Stanley Druckenmiller and Kenneth Langone, on the board, its access to capital is unusually strong.

Gary Cohn, the president of Goldman Sachs who also sits on the children’s zone board, said that while test scores were important, so was treating Harlem’s childhood asthma crisis, which is a cause of absenteeism.

"What it’s about to us is dealing with all of the issues these kids encounter," Cohn said.

The zone’s two charter schools are open to all city children by lottery. Officially, the schools spend, per student, $12,443 in public money and $3,482 in private financing each year. But that does not include the costs of an after-school program, rewards for student performance, a chef who prepares healthy meals, central administration and most building costs, and the students’ free health and dental care, which comes out of the zone’s overall budget, said Marty Lipp, the zone’s communications director.

Regular public schools in New York City spend about $14,452 each year per general education student, less than half of which is generally for classroom instruction.

In the tiny high school of the zone’s Promise Academy I, which teaches 66 sophomores and 65 juniors (it grows by one grade per year), the average class size is under 15, generally with two licensed teachers in every room. There are three student advocates to provide guidance and advice, as well as a social worker, a guidance counselor and a college counselor, and one-on-one tutoring after school.

The school, which opened in 2004, should have had a senior class by now, but the batch of students that started then as sixth-graders was dismissed by the board en masse before reaching the ninth grade after it judged the students’ performance too weak to found a high school on. Canada called the dismissal "a tragedy."

On a recent Thursday, the current high school students, neatly attired in blue and white uniforms, got special help in college note-taking skills and chatted animatedly about velocity in an advanced physics class. Most were well below grade level when they first got to the school and took three or four years to catch up; many are now ahead.

"You really have to put money into personnel," said Marquitta Speller, who has been the high school principal since January. "I don’t think you can experience the same level of success without the same level of resources."

But most of the seventh-graders, now starting their third year in the school, are still struggling. Just 15 percent passed the 2010 state English test, a number that Canada said was "unacceptably low" but not out of line with the school’s experience in lifting student performance over time. Several teachers have been fired as a result of the low scores, and others were reassigned, he said.

Giving administrators the ability to fire teachers for poor performance is one of the central suggestions of "Waiting for ‘Superman."’ Overall, 38 percent of Promise Academy I’s students in third through sixth grade passed the 2010 English test under the state’s new guidelines, placing it in the lower half of charter schools citywide and below the city’s overall passing rate of 42 percent. In Harlem as a whole, just 29 percent of children passed.

Promise Academy II, an elementary school that occupies part of a public school building, did better, with 62 percent passing in English, among the top 10 percent of charters. But because it lost more ground than comparable schools, it got a C from the city on its annual A-to-F report card, and an F in the student progress category. Both schools continued to outperform the city in math, with 60 percent passing in one school and 81 percent in the other.

A few recent studies have broached the question of what was helping the zone’s students raise attendance and test scores: the interlocking social services, or what was going on in the classroom? But they were based on state test results in years when the exams were easier to pass, and they may now be less conclusive.

One study, by the Harvard researchers Will Dobbie and Roland G. Fryer Jr., found that while Promise Academy students who entered the sixth grade in 2005 had raised their test scores so much by the eighth grade that they had "reversed the black-white achievement gap in mathematics" and reduced it in English, there was "at best modest evidence" that the social programs were driving that success. In 2009, nearly all the students passed the math test."

The challenge," the researchers wrote, "is to find lower-cost ways to achieve similar results in regular public schools."

For his part, Canada has achieved superhero status among those who admire him for the breadth of his vision.

"The fact that the impact has not been proven doesn’t mean that it doesn’t exist, because it is just very, very hard to prove something about an effort as multifaceted and interactive as this is," said Lisbeth Schorr, a senior fellow of the Center for the Study of Social Policy in Washington. "A lot of us feel you learn not just from research, but also from experience."

© 2010 The New York Times Company