Longer school days. More time for teacher training. Strong parental involvement.

These are the fundamentals of Atlanta's successful charter schools, and according to new test results, they are paying off.

Charter school students scored higher than those in traditional public schools in every tested subject on the National Assessment of Educational Progress, known as the nation's report card. And many of the city's 12 independent charter schools performed better on annual state assessments.

Critics say charter schools often get a better pool of students because parents must seek them out and apply to enroll. Traditional schools suffer, they say, because charters siphon funding and the most involved parents.

But supporters say these recent test scores show there are lessons to be learned from charter schools.

"This is a nationally based test, and it did show many of the charter schools are doing very well," said Tony Roberts, head of the Georgia Charter Schools Association. "I think that’s encouraging. Charters make a promise they will raise student achievement, and this is evidence they are doing just that, especially in Atlanta Public Schools."

An analysis by the National Alliance for Public Charter Schools showed Atlanta's charter students scored five points higher than traditional school students in fourth-grade math and reading, nine points higher in eighth-grade math and 12 points higher in eighth-grade reading. That trend was echoed in other urban districts around the country such as Chicago and Milwaukee.

Other Georgia districts take the national exam, but their scores are not released. Individual school scores are also not made available.

Victoria Trestrail enrolled her daughter at Atlanta Neighborhood Charter School near Grant Park because she liked the idea of smaller class sizes, creative activities and strong parental involvement. The school requires families to commit 20 hours to volunteering, which Trestrail and school leaders say plays a big role in the school's success.

Students at the school scored higher than the APS and state average on annual state exams in 2009-10, the most recent year available. The school also met annual testing goals known as adequate yearly progress, or AYP, along with eight other Atlanta charters.

"So much of the performance of students depends on the involvement of the family," Trestrail said. "Going to charter school, you have to apply -- it isn’t the default."

Not every Atlanta charter is succeeding -- four charters did not make AYP in 2011, and test scores at those schools trailed district averages in several subjects.

But Atlanta is considered one of the most charter-friendly districts in the state, and charter leaders say the district does a good job of applying some effective charter strategies to traditional schools. For example, the district is offering Saturday tutoring session for students who are struggling in math and reading.

"We embrace [charters] as a form of innovation," said Allen Mueller, director of the APS charter school office. "Given the challenges our children and families face and ever-shrinking education dollars, we need to think outside of the box."

Located in the East Lake community, Drew Charter has a longer school year, a longer school day -- from 8 a.m. to 4 p.m. -- Saturday school for struggling students and ample time to offer training to teachers. Principal Don Doran said his staff gets time for training two days a week, and estimates that by the eighth-grade, students have received an additional two years of instruction.

One of the city's largest apartment complexes feeds into the school, and 78 percent of its student population qualifies for free or reduced lunch. But its test scores are competitive with schools in Atlanta's affluent Buckhead neighborhood -- with 91 percent of fifth-graders scoring at or above grade level on state exams.

Parent Ellen Buettner calls Drew, a "a shining example of the way things should be done." But she doesn't send her daughter there. Instead, she attends nearby Toomer Elementary, a traditional school the family is very happy with. She originally had concerns about whether Drew had adequate funding, but now believes it can serve as an example to schools across the district.

"It’s about looking at each child and each school," she said. "Given the right resources – and the right resources are almost always good teachers – a high percentage [of students] can succeed."