In HS history classes, we were lucky to even GET to Vietnam. A lot of what I learned in history/civics I learned from reading on my own or asking older family members.
That’s how it was when I was in HS (’87-’90). There wasn’t even a section on the Vietnam War. I took an elective Social Studies class my Senior Year in HS — Current Events — and THAT is when I learned what I did about politics & events in the The Cold War Era & Vietnam - at least the parts I learned in school. But, I was lucky to have a good teacher, and I was lucky to have taken that class. Had I not taken that class the last required time period we learned about in History class was WWII and the period immediately following it!