Hartford (AP) - Connecticut has been given another year to work on changes as it launches a contentious set of school standards, federal and state education officials announced Thursday.

The U.S. Department of Education approved a February request by Connecticut officials to extend for one year a waiver from some provisions of the No Child Left Behind Act.

Federal education officials said the waiver, which now extends through the end of the 2014-15 school year, has helped schools improve student achievement and that the waiver may be renewed.

Waiver extensions also were granted to Arkansas, Colorado, Nevada, South Dakota and Virginia.

Kelly Donnelly, spokeswoman for the Connecticut Department of Education, said the waiver extension provides "additional flexibility" as Connecticut launches Common Core, a set of college- and career-ready standards.

Critics say it jeopardizes local control over education. and some teachers say they have been stymied by initiatives established with little involvement from those who work in the classrooms.

Gov. Dannel P. Malloy appointed a task force to review the rollout of Common Core.

President George W. Bush signed No Child Left Behind into law in 2002 to hold schools accountable for student performance. After initial bipartisan support, the law's popularity eroded as educators argued that many schools couldn't realistically meet the requirements and that it unfairly stigmatized some schools as failures.

U.S. Education Secretary Arne Duncan said Thursday the waivers have allowed states to "move beyond the one-size-fits-all mandates" of No Child Left Behind and be more innovative.

"As a result, we have seen a renewed focus by states on improving student achievement and to address the needs of all students, especially those groups of students that have been historically underserved," he said.

Connecticut's waiver, first announced in May 2012, gave the state more flexibility to spend federal money while not having to declare nearly half the state's public schools as failing.

President Barack Obama announced in September 2011 that his administration would grant waivers from parts of the law to qualified states in exchange for adopting college- and career-ready expectations for all students. States also have to set up accountability standards and teacher and principal evaluations that take into account student growth and other measures to help improve educators' work.