The U.S. Department of Education has granted a one-year extension for Minnesota's waiver to No Child Left Behind, the lapsed benchmark education law.

The extension is not much of a surprise. Federal education officials have often touted Minnesota's waiver to other states seeking to set up new school accountability systems and boost student achievement.

Under Minnesota's waiver, the Multiple Measurements Rating system was created. Among other things, the new ratings system recognizes a student's academic growth from year-to year, and how well a school is doing when it comes to closing the achievement gap between white and non-white students.

Under No Child Left Behind, about half of all schools were considered failures.

The law expired in 2007, prompting many states to seek waivers. Minnesota's plan was first approved in 2012.

“America’s schools and classrooms are undergoing some of the largest changes in decades—changes that will help prepare our students with the critical thinking and problem-solving skills that tomorrow’s economy will require,” U.S. Secretary of Education Arne Duncan said. “These extensions will allow states to continue the critical work of implementing the bold reforms they developed to improve achievement for all students.”

Forty three states currently have waivers in place. Without extensions, most would expire this summer.