Last year, I wrote a piece for CNN on how to teach 9/11 in public schools. That article will be part of a Twitter chat this evening at 9 pm eastern. The hashtag is #PTchat.

In brief summary, I argued that states should not require the teaching of 9/11, because states should generally refrain from requiring specific historical topics at all. If they go down that path, then everyone who thinks that X is important will demand that X be included in state standards to prove that the government cares. That’s why Illinois requires teachers to discuss Leif Erickson, the Irish Potato Famine, and the importance of trees and birds.  Long lists prevent curricular depth and diversity among schools. For instance, in Boston, 8th graders will focus on Reconstruction for several months, in partnership with Facing History. That would be impossible if they had to race to cover 9/11 by way of many other specified topics.

However, 9/11 is an example of a good topic to cover. It has the advantage of being recent, and too often, history class stops at World War II or the 1960s (in part because the accumulated state requirements take too long to cover). Ending more than a generation ago conveys the message that history is over and students have no role in it.

If teachers do elect to discuss 9/11 in social studies class, it should be treated relatively dispassionately, in a scholarly way, and students should be encouraged to consider the related controversies (such as whether the US should have invaded Afghanistan and Iraq as a result). We don’t want to indoctrinate kids with any particular view, but we do want them to learn to deliberate and reason about complex and contentious issues.

One subtle question is what counts as a legitimately open question for discussion, as opposed to a question that should be considered settled in a social studies classroom. (Diana Hess is the expert on this topic.) For instance, slavery is a settled question, but same-sex marriage, even though I strongly favor it, ought to be presented as unresolved. The suggestion that 9/11 was a US government conspiracy should not be treated on a par with the idea that al-Qaeda attacked the US. A student who thinks 9/11 was a conspiracy should be held accountable for providing very rigorous evidence (which I believe will be impossible). Nevertheless, the attack can be understood in several broader political contexts, and students should be encouraged to explore the controversies with due respect for evidence and logic.