It seems strange to organize an educational system around what can't be taught to children.

But for large chunks of the country, this is exactly how public educational standards seem to be set: by demarcating and preserving blind spots rather than promoting enlightenment.

It started at least 90 years ago with evolution, when Tennessee banned the teaching of any theory that contradicted the biblical story of the divine creation of man, leading to the infamous Scopes monkey trial.

The Supreme Court ultimately struck down such laws, but battles over teaching, or not teaching, evolution in public schools continue to this day. Many parts of the country that have relaxed their objections to teaching evolution have now pivoted to try to ban or sabotage teaching about climate change. Sex ed - at least the kind that actually educates kids about sex, rather than its absence - has come under similar attacks. Now, more recently, states have started trying to ban the teaching of U.S. history.

Yes, U.S. history. Specifically, the bits of our history that might be uncomfortable, unflattering or even shameful - or, as some politicians call it, "unpatriotic."

This week an Oklahoma legislative committee voted overwhelmingly to effectively ban the teaching of Advanced Placement U.S. history classes.

The bill's author, Republican Rep. Dan Fisher, said that state funds shouldn't be used to teach the course - which students can take to receive college credit - because he believes it emphasizes "what is bad about America" and characterizes the United States as a "nation of oppressors and exploiters." Fisher's proposal to replace the ready-made, nationally used, college-recognized AP curriculum - studied by hundreds of thousands of high school students each year - with a homegrown substitute would cost the state an estimated $3.8 million.

After facing national criticism, Fisher withdrew his bill and said he plans to submit a new one requiring a state "review" of the AP course rather than its complete defunding. But Oklahoma is far from alone in wanting to reinvent the wheel by creating its own, allegedly more patriotic version of advanced coursework. Policymakers in Georgia, Texas, South Carolina, North Carolina and Colorado have agitated to scrap or doctor the AP course, citing its "liberal bias" and supposed focus on U.S. "blemishes."

The Republican National Committee likewise called on Congress last year to withhold funding from the nonprofit that developed the course, the College Board, because its AP course "emphasizes negative aspects of our nation's history while omitting or minimizing positive aspects."

In Colorado, where a local school board proposed revamping the AP curriculum to make sure it does "not encourage or condone civil disorder (or) social strife," some brave students decided to demonstrate the virtues of civil disorder and social strife by peacefully protesting.

The objections here are not just about insufficiently patriotic content but a bizarre, almost obsessive paranoia about federal encroachment upon states' rights. Some legislators seem convinced that the educational standards set by the Common Core and AP and IB tests are a manifestation of federal tyranny - an odd concern, given that (A) none of these curricula was developed by the feds (Common Core was a state-led effort, and AP and IB programs are overseen by independent nonprofits) and (B) none of these curricula has actually been mandated by the federal government.

AP and Common Core standards also give teachers and schools quite a bit of discretion in what they teach, setting broad critical-thinking goals rather than providing a concrete syllabus, textbook or packet of lesson plans.

If an AP U.S. history teacher wants to highlight the heroism of our Founding Fathers, he very much can.

All said, it's unclear what problem these states are trying to solve by making it harder to offer classes that will help driven and ambitious students succeed.

In the short run, developing new, more politically compliant curricula, and then training teachers in it, is expensive. But the costs in the long run are much higher. For one, dismantling AP classes will limit students' ability to get college credit for their high school studies in an era when it's already taking ever longer to complete what's supposed to be a four-year degree. More important, setting politically motivated ceilings on what students are allowed to learn will ultimately make them less informed citizens, likely dooming them to support passing equally dumb public policies as adults. Those who don't know history, after all, are condemned to repeat it.