WASHINGTON, D.C. – Tipping points come in a variety of forms.

Those pivotal moments in life when the impossible becomes inevitable, and vice versa, can be immediately obvious (i.e. the Supreme Court’s “Obamacare” ruling) or only apparent over time (i.e. the 1972 Watergate break-in).

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The nation’s Common Core experiment may have experienced its own tipping point this week – going from an absolute certainty to a likely failure – with a surprise announcement from the head of the nation’s largest teachers union.

On Wednesday, National Education Association President Dennis Van Roekel published a letter blasting the “botched” rollout of the standards in the nation’s schools and calling for a “major course correction” comprised of more time, money (of course) and a delay in linking teachers’ job evaluations to students’ Common Core-aligned standardized test scores.

Van Roekel writes:

“I am sure it won’t come as a surprise to hear that in far too many states, implementation has been completely botched. Seven of ten teachers believe that implementation of the standards is going poorly in their schools. Worse yet, teachers report that there has been little to no attempt to allow educators to share what’s needed to get (Common Core) implementation right.  In fact, two thirds of all teachers report that they have not even been asked how to implement these new standards in their classrooms.”

Other unions – including the American Federation of Teachers – have already soured on Common Core, but Van Roekel’s announcement is different. That’s because the 3 million member-strong NEA has been a major supporter of the nationalized learning standards, even going so far as to pledge “that its members would hold town-hall forums, speak at PTA meetings and do everything they could to persuade a wary public to give Common Core a chance,” POLITICO.com reports.

That commitment was made, in part, because the union has received millions of dollars from the Bill & Melinda Gates Foundation to promote Common Core, according to POLITICO.com.

But now the union can no longer deliver on those promises, given that so many teachers have become disillusioned with how Common Core is affecting them, their students, and their profession in general, the news site adds.

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It’s true that Van Roekel’s letter contains the obligatory vote of confidence in the ultimate goal of Common Core, but the overall tone of his missive has an unmistakable “Let’s be friends” quality, rather than a “We’ll get through this together” one.

And that should have Arne Duncan, Bill Gates, Jeb Bush and the other Common Core purveyors more than a little worried.

Common Core has never been field-tested

One of Van Roekel’s major complaints against Common Core mirrors that of Tea Partyers, namely that the standards were never piloted in an actual school before being adopted by some 45 states.

In his letter, Van Roekel addresses that concern by writing that teachers need “time to field-test the standards in classrooms to determine what works and what needs adjustment.”

A few paragraphs later, he adds: “Governors and chief state school officers should set up a process to work with the NEA and our state education associations to review the appropriateness of the standards and recommend any improvements that might be needed.”

Those two sentences get to the heart of all criticism that’s been directed at Common Core, namely that the standards were forced upon the states before they were field-tested in actual classrooms to determine if they are as “rigorous” and “high quality” as advertised.

Van Roekel’s words serve as indisputable proof that the powers behind Common Core purposefully rushed the standards into place before anyone could properly evaluate them. They did so because they knew the American people are committed to the principle of locally controlled education systems and would resist any centralized effort to bring uniformity and nationalized standards to their neighborhood schools.

‘It’s malpractice’

Van Roekel’s other major Common Core criticism revolves around the linking of students’ Common Core-aligned assessments to teachers’ annual job reviews.

The union head notes that some states are teaching the new standards but using old tests that were designed for the previous set of learning objectives. Meanwhile, at least two states – New York and Kentucky – are giving Common Core-aligned tests while teachers are still struggling with how to teach the new math and English standards, which allegedly emphasize “critical thinking skills.”

“It’s beyond me how anyone would ask teachers to administer tests that have no relation whatsoever to what they have been asked to teach. In too many states, that’s exactly what’s happening,” Van Roekel writes.

“And, then, to make matters worse, many states are proceeding to use these invalid test results as the basis for accountability decisions,” he adds. “This is not ‘accountability’ – it’s malpractice.”

Other major teacher unions, such as the AFT and the New York State United Teachers, have already turned against Common Core for similar reasons. The union resistance presents a major problem for Common Core defenders.

One guess is that Common Core supporters will try to keep the unions on their side by offering some kind of deal that keeps the standards and assessments in place, but lessens (or negates) the consequences of low test scores on teacher evaluations.

That would be a ground-shaking development, but one to watch as Common Core defenders become more and more desperate to stop the bleeding away of allies.

It’s far too early to know if Common Core is headed for the ash heap of (K-12) history, or if this learning experiment will survive simply because it’s so cemented in place that nothing short of a political earthquake of historic proportions can shake it loose.

We’ll see.

But if Common Core does go the way of the many other educational fads that preceded it, we may look back at Van Roekel’s letter as the tipping point – when the nationalized standards went from inevitable to untenable.