Sunday was the 10th birthday of the No Child Left Behind Act, the federal government’s signature education law.

You probably didn’t notice a lot of partying, though, because in keeping with numerous decades of federal meddling, the act’s been an expensive dud.

NCLB — really just the latest iteration of the Elementary and Secondary Education Act of 1965 — certainly has been lame.

Despite federal k‑12 spending rising from $27 billion in 2001, the year before NCLB, to $38 billion in 2011, reading and math scores on the National Assessment of Educational Progress — the so-called “Nation’s Report Card” — have either been stagnant, or grown at slower rates than many periods before No Child.

So, overall progress has been underwhelming.

But No Child Left Behind did one good thing. By requiring disaggregation of test scores for numerous groups that have historically struggled, it has shone bright sunlight on neglected, cobweb-enmeshed classroom corners.

Right?

Hardly.

For one thing, education bureaucrats around the country created wildly varying tests, definitions of “proficiency,” and played lots of other tricks that have made it nearly impossible to know if a child is truly proficient, or just so labeled by a system dodging punishment.

There’s also a serious question of whether rising test scores for historic strugglers have reflected increasing knowledge or just better testing strategies.

And then there’s outright cheating, with which Georgians are all too familiar in the wake of the cheating scandals in Atlanta and now in Dougherty County.

In other words, rather than sunshine, in many cases NCLB has created a bright, shining lie.

NCLB has been a failure. Ultimate blame, however, doesn’t rest with the law. It rests with the basic reality of how federal policy is made.

The fact is that Washington has been heavily involved in education since the mid-1960s, and longterm test scores evince little evidence that, outside of desegregation, it has done any good.

Indeed, NAEP scores for 17-year-olds — basically, our schools’ “final products” — have been almost completely stagnant since 1970.

Meanwhile, inflation-adjusted federal spending per pupil has grown nearly 400 percent.

Why was so much invested, for so long, with so little return? Because federal politicians don’t have to worry if the spending does any good.

What’s important is keeping happy the people who hold the most power in education politics — the teachers, administrators and others whose very livelihoods come from taxpayer funding — and that means coupling ever-more money to Potemkin accountability.

Parents and taxpayers also might be considered, of course, but with full-time jobs and myriad other concerns, they can’t and won’t sustainably project force in education equal to that wielded by those who would be held accountable.

The only way around this fundamental political problem — those you want held accountable exert the most sway over the politicians who hold the hammer — is to get politics out of education.

At the federal level, that means removing Washington completely from the classroom, a place, not coincidentally, in which it has no constitutional authority to govern anyway.

After 10 years of No Child Left Behind, and approaching 50 years of overall federal failure, there simply shouldn’t be any further question: It’s time to get Washington out of education.

Neal McCluskey is associate director of the Cato Institute’s Center for Educational Freedom and author of the book “Feds in the Classroom: How Big Government Corrupts, Cripples and Compromises American Education.”