IN highschool, it depended on the teacher. I had ones where they just told you the major points (starting date, ending date, who won, who lost, and we briefly talked about France's fuck up in the region before the US). I had ones who went into great depths about it, (talking about the politics of the region, why the US failed, why the vietcong were able to hold out so well, how it can be applied today and [then] the war in iraq, and that is still going on in the Middle East).
In my high school, we were a bit odd.
<spoiler=ninth grade>In ninth grade (first year of high school, 14-15 years old), we covered US government, the politics, a greater depth of how laws are made, the checks and balances, how some of the greatest amendments came about, etc.
<spoiler=tenth grade>In tenth grade (second year of highschool, 15-16 years old), we covered colonial foundings, starting wtih 1000 AD, and went up to the civil war, with the last big thing you learned being the utah wars and Buchanan's failure in office. We dealt with things other then the US as well, like the French Revolution, the Spanish Inquisition, the Haitian Rebellion, the introdcution of the magna carta. Just some major things in history that it seemed sorta wrong to gloss over.
- you could also take an optional second history class, which dealt with the general overview of world history, which was very simplistic since there was a lot to cover, and mostly dealth with sociological things more so then the history (which I took as well).
<spoiler=eleventh grade>In eleventh grade (third year, 16-17), you learned about the Civil War, and went up to the end of the korean war as one of the first major conflicts that would be encompassed in the Cold war. There you learned things like the Major politics and battles of the Wars, including the British involvement in Civil War and how it could have been much worse for the Union had they lost a few of the early major battles like Antietam, the realities of Germany being forced to Start WW2, how communism afftected the world at the time, the dick measuring contest the US and the USSR seemed to be waged in and things like the Ghandi leading for a free India.
<spoiler=twelfth grade>In twelfth grade (fourth and final year, 17-18), you learned of after the end of the Korean Wars and up to Present (which we were lucky, we got funding at the time that let us buy the most recent books, instead of having to end at 2008, with the Obama election being the big news (which then was old news by two years). You learned about Viet Nam, about France fucking it up, about America attempting the clean up and again fucking it up, about how actually now having pictures and wide spread media coverage changed the opinion of war and how it would affect its citizens, about how the social movements such as the civil rights and hippie movements changed America. About the Collapse of the USSR, the Nixon debacle and Ford's presidency, the Gulf War and why Bush (sr) wasnt elected into office, and how Clinton gave the country a brief taste of happiness and bliss, about 9/11, the training that the us went through with Osama and how he eventually turned to bite us in the ass, and even some of how Libya is now like it is with the UK setting up that government).
So really you had the chance to learn alot or a little, it just depended on the teacher and the grade youw ere in. You still learned the major points, and (at least at my school) we didnt just gloss over the Viet Nam war (Or the War of 1812 for that matter, though we could have for all that it accomplished and all the pathetically weak reasons the war was even started).
EDIT: edited it with spoilers so its a bit easier to read.
EDIT 2: And honestly, I learned more from my uncles, specifically my one uncle who's always around cause he still lives close since he was in Korea and Viet nam. I had a I think 4 uncles in Korea and three in Viet Nam (including the one who lives close to me) and two that fought in both, and all any of them ever say is we shouldnt have been there and tehy just cant hate the Vietcong for killing Martin (uncle that died in Viet nam). That and my grandfathers always tells them that he pities them for having to fight that war, and by comparison WW2 was the easier war to fight in.