I've had to educate myself a lot more about american history than I was taught in highschool. Logical ofcourse as I'm Belgian, I think that my history classes overall were pretty extensive though. Aside from just European/Belgian history we also learned in-depth about middle-eastern and African history.
American history was fairly brief aside from Columbus' arrival.
Besides that there were a few smaller chapters on slavery, the civil rights movement and the civil war. Martin Luther King and Malcolm X both had large chapters though and I remember having to write a paper on one of them. Other than that I didn't really know much about the US' history.
Something I definitely feel I had to learn mostly on my own was finances, insurance, stocks, the job market, ...
We really didn't get proper preparation for our future finances and costs as an adult. It's definitely something that is a nation-wide problem, not just my school. When I graduated I didn't even know how our taxes worked.
I would've gladly traded a little less history or language classes for some more of the above.