Post-pandemic: Travel. Nothing in the school curriculum can teach what travel can. Books only do so much. If unable, game with people from other countries and talk to them. Talk to people from other countries. Strike up a conversation and listen. Use the internet and international video gaming to your advantage. Books are so full of assumptions of other cultures, so many mistakes, and you don't get the truth unless you've actually been there or know someone who is there. There are a couple ways of traveling for free or low cost included but not limited to: find jobs that seek Americans in the country you're curious about, find a nonprofit that sends you over somewhere for a good reason, or join the Peace Corps. If you live your whole life without ever leaving the country, you have no idea what you're missing. Seriously. Also note: if your job requires you to be a desk jockey and you only need an internet connection to get to work, who says you have to stay in one place anymore? The digital nomad lifestyle is not just for perfect-life-sellers with an Instagram account anymore. Something like 40% of the US population is now working from home. If you can work with just an internet connection, then you can work from anywhere in the world that has one.
Guide to cheap travel abroad Nomadic Matt, Migrationology and The Broke Backpacker
CIA World Factbook and ThoughtCo Articles for Geography
I highly recommend that if you are unfamiliar with war, you ask a veteran friend if they know anyone who would be willing to talk to you about it. Civilians don't know anything about it. Not a damn thing. We can only get closer to the truth, and the only way that's gonna happen is by hearing it from people who have been there.
State Symbols USA New 8/25/22 Contains lots of little-known information about all 50 states
Native-Land.Ca Ever wondered where Native tribes' territory actually is, historically and currently speaking? This map endeavors to show you. It is not perfect and it is not definitive but it is certainly helpful. It's gotten better recently, since it branched out internationally and added Aborigine tribal territories, South American tribal territories, and more. It seems to have started branching out into Africa, which is really good because in the Northern Hemisphere that is a massive blind spot in our education system. I recommend that you figure out what tribal territory you're currently on at the moment using the map just to learn that for starters.
DOI Indian Lands Map This is the US Government's "official" Indian Lands map. It is sanctioned by the law and indicates the exact boundaries of Native American sovereign nations within the United States. These places are just as important to learn as the 50 states plus the other assorted territories like Puerto Rico and the Virgin Islands. You know what's odd? The fact that these sovereign nations do not have their own constitutional delegates or senators like the 50 states do, and the laws of the United States are not quite the same as those on NDN land. They don't have representation at the federal level and the legal system for NDN sovereign nations is strange. Hmmmm.
CGP Grey Miscellaneous Social Studies topics
Illuminaughtii Youtube Channel
Sociology
Steak-Umm's Twitter Megathread Also contains basic critical thinking info
The Evolution of Trust: intro to game theory
The Crowd by Gustave LeBon A book on mob mentality. Sexist, racist, flawed, and heavily reliant on assumption, it is very much a product of its time. It is still worth reading.
Implicit Bias Test These include bias tests for racism, ableism, and other things. Provided by Harvard University. Test yourself, see what you get. Take it with a grain of salt though.
TV Tropes especially Old Tropes
National Geographic for Kids Contains a great deal of cultural, historic, geographical, and Earth science types of information, and more. Not just for kids and impressive.
National Park Service Same deal as National Geographic for Kids; lots of information here, available to all, impressive.