SAN FRANCSICO (AP) — Eight of California's largest school districts can ignore parts of the No Child Left Behind education law, Education Secretary Arne Duncan said Tuesday in announcing the first district-by-district waivers he had long tried to avoid.

More than 1 million students were covered under the California decision, which includes schools in Los Angeles and San Francisco. In exchange for permission to ignore requirements that all children perform at grade level in math and reading, the districts promised school improvement plans that include adopting Common Core standards this fall and testing students on those academic benchmarks starting the following school year.

California did not petition for a statewide waiver from the law, and most districts in the state still would be bound by the Bush-era law. The eight districts that went around the state education officials banded together as the California Office to Reform Education, or CORE.

"The CORE districts have been engaged in collaboration and innovation designed to promote deep student learning and effective implementation of new standards that will prepare students for college and a career," Duncan said in announcing his decision.

Yet Duncan had long tried to avoid district-by-district decisions on No Child Left Behind waivers.

"My strong preference is to work with states," Duncan told reporters in February. "We can manage a portfolio of 50 states. Managing a portfolio of 50,000 districts is lot more difficult."

At the time, he strongly urged California and other hold-out states to petition for statewide waivers.

But they did not. And absent a statewide petition from a state, Duncan decided to award waivers to the major districts in California, which also included Sacramento, Fresno, Long Beach, Oakland, Sanger and Santa Ana school districts.

School chiefs given flexibility praised Duncan's move, while his Republican adversaries in Washington pilloried it.

"We deeply appreciate Secretary Duncan and the Obama administration for reviewing and ultimately approving our districts' plan to improve teaching and learning through collaboration and capacity building," said Michael Hanson, superintendent of Fresno Unified School District and president of the CORE coalition.

The Republican chairman of the House Education Committee said the decision would only add a headache to local officials.

"As if state waivers weren't convoluted enough, the administration has now decided to move forward with district-level waivers," said Rep. John Kline, R-Minn. "One can only imagine the confusion this creates for families, teachers and state and local education leaders."

Other conservatives were likely to seize on the California districts' embrace of Common Core, a system of academic standards designed to provide consistent guidelines for students, parents and teachers. Forty-five states and the District of Columbia have adopted those standards, which conservatives have compared to a national curriculum and have tried to roll back their adoption.

No Child Left Behind, also known as the Elementary and Secondary Education Act, came up for renewal in 2007 and its requirements were not updated. Duncan has pushed lawmakers to revisit the law and make changes to accommodate challenges officials did not anticipate when they first passed the measure on a bipartisan basis in 2001.

The House has passed a rewrite of the law that targeted Common Core Standards.

A competing rewrite has been completed in the Senate Education Committee but a vote on that version has not been scheduled, meaning schools are still being held to the over-ambitious goals of the decade-old law unless Duncan gives them waivers.

"Today's waiver approval for CORE relieves school districts overseeing an enormous number of children in California's education system from the burdens of the more onerous provisions of No Child Left Behind. While necessary, however, this is not an ideal solution to improving educational outcomes for all children in California," the Senate education panel's chairman, Sen. Tom Harkin, D-Iowa, said. "Now more than ever we need to reauthorize the Elementary and Secondary Education Act in order to ensure that all students can benefit from a stronger, more transparent education system."

To this point, Duncan has given 39 states and the District of Columbia permission to ignore parts of the law. In exchange for the waivers, states have had to show the Education Department they had their own plans to prepare students and improve teaching. States have sought the additional flexibility to implement their own efforts instead of following the sometimes rigid requirements included in No Child Left Behind.

The waivers also allow states to come up short on requirements that all students perform at grade level in math and reading by 2014.

If Congress were to update No Child Left Behind, the states would be forced to shift to the new national standards — potentially a headache for states that already have set forth on their own individualized plan