Updated

North Carolina and Tennessee will be allowed to change the way they measure student progress under the federal No Child Left Behind law, the only two states chosen for a national experiment.

The Education Department announced Wednesday that the two states may track how individual students perform in math and reading over time, known as a "growth model."

Until now, states could only measure success or failure by comparing the scores of different groups of children from one year to the next. Many educators say that system is unfair because it does not recognize changes in the population or improvement by individual students.

Education Secretary Margaret Spellings also announced changes involving tutoring and schools affected by Hurricane Katrina, part of a campaign to show flexibility under the law.

How progress is measured is hugely important to schools, because it helps determine whether they meet their goals — and avoid penalties — under the education reforms passed by Congress in 2001. States have been clamoring for a different way to judge student success.

Of the 13 states that sought approval to track individual students over time, only two were approved. Spellings had planned to allow up to 10 states in the pilot project this year, but other states didn't qualify, mainly because they lacked sufficient data.

"We set a high bar, admittedly, because we really wanted to get good information," said Henry Johnson, the assistant secretary for elementary and secondary education. "I certainly would have liked to have had more."

Six states that had made the final cut were rejected: Alaska, Arkansas, Arizona, Delaware, Florida and Oregon. Five other states that applied — Colorado, Indiana, Iowa, South Carolina and Utah — were rejected earlier because their proposals did not meet the terms Spellings set out last fall.

North Carolina and Tennessee schools will be able to choose how they measure student progress — the old way or the new way.

The two states were picked, officials said, because they have data systems to track individual students — including all children in required testing — and they committed to closing achievement gaps between whites and minorities. The two states will also track whether children who are already at grade level are still improving.

Every state must get every child up to par in reading and math by 2014.

States may apply again next year to track individual students' progress. The six that made it to the final round this year will get early consideration if they apply again.

Arizona was the only state recommended by peer reviewers but not chosen to take part. The department rejected the state's plan because of an unresolved dispute about how Arizona handles appeals from schools that fail to make yearly progress.

Under the law, schools are required to test students in math and reading in grades three to eight and once in high school. Schools must show yearly progress overall and among groups of students as defined by race, disability, English language ability or economic situation.

Spellings also announced:

—All states can apply to offer tutoring in their struggling schools before they must offer transfers to students, reversing the order of consequences the law requires. Spellings said such an experiment in a few Virginia school districts has proven a hit with parents.

—Six states that have accepted high numbers of students displaced by Hurricane Katrina will get flexibility this year. The states will not be held accountable for missing their yearly progress goals if the sole reason was the test scores of the newly enrolled kids. Those six states are Alabama, Arkansas, Georgia, Louisiana, Tennessee and Texas.