If you can find a way to teach that without violating the Establishment Clause, sure. The only way forward I can see here would look like a comparative history of religions course, which would teach various creation stories from a neutral viewpoint. And that doesn't seem to be what those campaigning for anti-evolution education have been looking for. Curious if you've got any fresh ideas, though.

Maybe that was a bad example. What if instead of something religious, there was a class teaching some kooky conspiracy theory as fact, like a physics elective saying that perpetual motion is possible, but that the patents to make it work well enough to overcome friction have all been bought up by Big Oil and suppressed?

It would need the support of textbook companies to print it, school boards to buy into it, teachers to deliver it, and students interested in taking it. There's a whole marketplace of ideas out there, and the course you're proposing simply wouldn't survive it.

Teaching intelligent design needn't violate the Establishment Clause. Nobody says schools can't mention religions and what they believe, just that they cannot require students to adopt one.

Using taxpayer money to promote religion has been held to be equivalent to an "establishment" of religion. This means that any schools funded by the tax man have to be strictly secular, even in their "elective" activities.

The language I used allows that possibility. But, in the specific legal challenges I'm aware of in this area, that's been the constitutional obstacle to teaching creation as fact.