WASHINGTON - Six states are getting the OK to write their own prescriptions for ailing schools under the Bush administration's signature education law.

It's a softening from how No Child Left Behind currently works - with schools having to take certain steps at specific times for missing math and reading testing goals. Critics have complained that the approach is too rigid and treats schools the same regardless of whether they miss the mark by a little or a lot.

The states getting more freedom under a pilot program are Florida, Georgia, Indiana, Illinois, Maryland and Ohio. Education Secretary Margaret Spellings made the announcement during a speech Tuesday in Austin, Texas.

North Dakota is among states that unsuccessfully applied for federal permission. State School Superintendent Wayne Sanstead said the rejection largely was a result of federal officials not understanding North Dakota's rural nature.

He said federal officials cited as reasons North Dakota's lack of school choice; lack of charter schools, which are independently governed public schools; and lack of supplemental education services.

North Dakota has no charter school authorizing legislation, supplemental education services are not economically viable and most North Dakota towns can only support one school, Sanstead said.

"It was very clear that they didn't take into consideration the ruralness of the state," he said.

Sanstead said North Dakota's proposed plan focused on helping schools that are just shy of making required annual progress under No Child Left Behind, rather than lumping them in with schools that are far from meeting goals.

The states that won approval have come up with plans to more closely tailor solutions to individual schools' problems and focus resources on schools in the worst shape.

"We expect to see a closer fit between the causes of school underperformance and a focused attention at repairing those sources of failure," said Margaret Raymond, director of an education think tank at Stanford University and the chair of a panel that reviewed the state proposals.

Examples of changes the states plan to make include requiring schools to offer tutoring earlier than is currently called for and a greater reliance, in Indiana for example, on testing throughout the year to catch academic weak spots.

In Florida, schools with low-performing students will likely be assigned teachers who have experience teaching similar students successfully.

Maryland is placing more emphasis on training principals. It's common under the law for failing schools to replace their principals. "We think principal leadership is key. It's not just changing a principal, it's ensuring principals have the necessary skill sets," said Maryland schools superintendent Nancy Grasmick.

In Georgia, the state is spelling out that schools can become charter schools, which are public but operate with broad independence, earlier than is currently called for, said the state's superintendent of schools, Kathy Cox.

Some critics worry the changes, specifically the focus on the worst-performing schools, will take the pressure off schools that are generally doing well but having trouble with one group of students - such as a minority group or kids with disabilities.

"I don't think it's taking the pressure off. I think it's allowing focus," Cox said.

Spellings has said up to 10 states will be allowed to try to participate in the pilot program. The Education Department plans to review additional state proposals this fall. Sanstead said he is hopeful that North Dakota's plan will be reconsidered.

The six states that won approval were among 17 that sought it.

The other states that didn't win approval were Alaska, Arkansas, Louisiana, New Jersey, New York, Oklahoma, Pennsylvania, South Carolina, Tennessee and Virginia.

Spellings said in an interview that the efforts by the states that won approval to try new approaches will be closely watched and will shape any future rewrite of the six-year-old No Child law.

"We're trying to set the table for a strong and sensible reauthorization," Spellings said. "We're going to learn some things."