Traditionally, the "line" in public K-12 education is facts not proselytizing (ie "The Mormons settled Utah in the 1800s" good, "The Mormon faith is superior", bad). The problem is that at some point, kids need to be taught opinion, analysis, and discourse, which rather invites editorialized statements (ie "Columbus: Great explorer, Native American oppressor, or both?"). In my day, "Huckleberry Finn" had to be defended against those offended by the n-word adjective (but that was an attempt by Twain to explain historical fact, not proselytizing I'd say), my son's English ed required more Tennessee Williams and feminist lit, which flirted with some rather LG proselytizing themes, but we never complained. The Alamo is rather complex (having been there a few times, read extensively etc), so here goes: "The Alamo battle became a rallying point for what was then thought by American settlers and Tejanos to be oppressive measures by Santa Ana and the Mexican government. It may also have been part of an American land grab at the expense of many Mexican nationals, caught in the middle." Facts not proselytizing? Of course if you don't like all this, get home schooled or go to private school!

Note: Davy Crockett meets the hero "looks like a duck, quacks like a duck" test, which means if people think he was a hero, then he is a hero. He also comes out of the Andy Jackson/Cherokee thing awfully well. Not perfect but pretty damn good, and I'm not apologizing for running around in a coonskin cap as a kid.