While I typically avoid touching non-technical topics, I have the opportunity to chime in as another PA highschooler from the 90's, we absolutely were taught that, down to details in AP courses such as the impact of individuals like John Brown. While I'm not sure I'd have worded it precisely like the parent, the concept of "the four boxes of liberty" and the progression thereof was certainly understood and conveyed. (There was substantial study of the labor rights movements and conflicts/resistance therein as well)

I went to Jesuit high school in Chicago in the early 1990s. There's a lot more to say about all of this stuff and nothing wrong with what you just said, but to hash it out any further, we'd have to attempt a philosophical discussion about violence in a forum that (unavoidably, and to the consternation of its moderators) has reward circuits wired around hyping up action.

“The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants” has been a popular quote in the US for a long time.