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)