The Network for Public Education, a nonprofit education advocacy group co-founded by historian Diane Ravitch, is calling for a national “opt out” of high-stakes standardized testing, urging parents across the country to refuse to allow their children to participate in this spring’s testing.

In a video released on the network’s website, Ravitch says families should opt out of state-mandated high-stakes testing in part because the scores provide “no useful information” about the abilities of individual students and are unfairly used to evaluate educators. She also notes that testing and test prep take up valuable class time that could be better put to use providing students with a full curriculum, including the arts.

“Opt out is the only way you have to tell policymakers that they’re heading in the wrong direction,” Ravitch says in the video, aimed at parents.

Ravitch has been the titular leader of the movement against corporate school reform since the publication of her 2010 book, “The Death and Life of the Great American School System,” which explains why she had abandoned her support for No Child Left Behind and test-based school reform. From 1991 to 1993, she worked as assistant secretary in charge of research and improvement in the Education Department of President George H.W. Bush and served as counsel to then-Education Secretary Lamar Alexander. She was a supporter of No Child Left Behind, the chief education initiative of President George W. Bush, until she researched its effects on schools and students and concluded that it led to a narrowing of curriculum, an obsession with test prep and demoralized teachers.

What has become known as the “opt out” movement has been growing in various states for a few years, sparked by standardized test-based school reform that began under the administration of the younger Bush and gained steam under President Obama. A growing number of parents are refusing to allow their children to take tests that they believe — and that assessment experts say — are being used in an improper manner to evaluate students and teachers.

Last year, the opt-out movement was strongest in New York state, where about 20 percent of students refused to take the state’s “accountability” test, but tens of thousands of students in other states did the same thing. In fact, the U.S. Education Department issued more than a dozen letters to states where opt-outs were reported, warning them of possible sanctions if at least 95 percent of all students are not tested. The 95 percent threshold is set in federal K-12 education law, first in No Child Left Behind and then in its successor, the Every Student Succeeds Act.

In New York, officials reacted to the opt-out movement by making the mandated tests shorter, removing time limits and temporarily saying that the scores won’t be used to evaluate teachers for years. Betty Rosa, the newly elected chancellor of Board of Regents, the state’s education policy-making body, said that if she had children who were of an age to take the state-mandated Common Core tests, she would keep them home on testing day.

The Network for Public Education is a coalition of dozens of groups that advocate for public education. It recently issued a state report card that evaluated states on criteria seen as promoting a professional teaching force, equitable and sufficient funding, and equal opportunities for all students to succeed.

The nonprofit National Center for Fair and Open Testing, known as FairTest, which fights the misuse of government-mandated standardized tests, says on its website that the average student takes 112 tests between kindergarten and 12th grade and that the assessments “are frequently used in ways that do not reflect the abilities of students of color, English language learners, children with disabilities, and low-income youth.”

Indeed, Yohuru Williams, Fairfield University professor and a board member of the Network for Public Education, has argued that annual high-stakes testing feeds racial determinism. He said in a statement:

“Choosing to opt out is one way of fighting back against the tide of corporate education reform with its emphasis on high-stakes testing, which has had a traumatizing effect on young people. We have a moral responsibility to demand that the government attack the real source of inequality in American society, which is poverty, rather than promoting schemes that discourage rather than encourage social justice.”

Both FairTest and the United Opt Out National, a grass-roots organization affiliated with the network, have information on their websites about opting out. FairTest says that despite threats from policymakers, it knows of no school or district that has been sanctioned for testing opt-outs.