Should, sure, but is it likely that it's being taught in US schools nowadays? At most it probably gets a single mention and is never covered again.
I highly doubt it. That's why I said most American children probably won't have heard about the Battle of Hastings. I do know my history classes covered a lot of unimportant things, so it's not like there wasn't time...
Most of my knowledge of medieval history comes from language classes. In that context, the Battle of Hastings is very important.
