What place do I get teleported to? If I’m teleported to the same place on Earth, then I just fell down several meters into a swamp and am probably going to die here.

I would teach London children the most obnoxious brain rot slang from today as a laugh.

Wouldn’t I be in like empty space?

1375? Die from malaria, I guess? Be eaten by an alligator? Or oh no, hasten the demise of the Tocobaga with my exotic biology? Either they would kill me or get me sick, or vice versa. Also, fall on my ass when my house disappeared.

I would follow the river to the bay, I guess, and see if I could find anyone, or anything I might be able to eat.

I would kill everyone I meet with the plagues I carry which I’m immune to.

I would warn the Native Americans about the Europeans

Die because my medications haven’t been invented yet.

Or be murdered because I’m not christian

Double entry accounting system.

I’m an accountant by trade. The double entry system wasn’t invented until the 15th century.

I could account for any lords various assets, goods, and livestock in an efficient, reliable and accurate manner

This is very A Connecticut Yankee in King Author’s Court

https://en.wikipedia.org/wiki/A_Connecticut_Yankee_in_King_Arthur's_Court

I hated that book. So pretentious.

Die as you forgot to teleport me to where the earth was at the time.

Otherwise I guess my main knowledge that could be useful is some basic first aid. Secondary to that, a little bit of electrical stuff.

Well, staying in the same location? I’m in the US, so… I’d probably try to get writing invented. To my knowledge, besides some of the Central American empires, there’s no evidence or even claim of there having been any kind of writing or system for making information durable. I know there’s a lot of clay here, I’m pretty sure we could bake clay tablets to store down information. There’s also tule reeds here that were already being extensively used, and those could probably be made into a kind of paper as well. As to whether the people would accept that, I have no fucking idea at all; what we know of the California tribes suggests they were always semi-nomadic, but that’s all very well into the post-contact period and much of what we know was written down by the Spanish while being the biggest bastards they possibly could to the locals. I dunno how useful record-keeping would be to a nomadic people. It’s also entirely possible the people would be like “uh, yeah, we know how to write, dummy”, and it was just lost in the multiple waves of pandemics.

I think probably something that -might- be achievable is figuring out glass. I’m mostly sure that if the native Americans had glass, we would have seen some sign of it in the archeological record by now. I’m sure some smarty pants is going to come along and tell me “you can’t just throw sand in a kiln and make glass, you need a special kind of sand blah blah blah and here’s 99 reasons why that won’t work”. Yeah, you’re probably right, but I don’t know any better, so I’d still definitely try. I also remember reading that clear glass was a thing figured out near Venice when they started adding grass ash or some shit to the sand, so I’d definitely experiment with that, too. Glass is just dead useful -and- pretty, so I’m fairly confident I’d get some acceptance that way.

I would say metal smithing, but the only metal deposits nearby that I know of are mercury and gold. You can’t make nails and tools out of mercury and gold.

Also, maybe water wheels? To my knowledge, we have no record of native Americans using water wheels for work (I.e. grinding corn or acorns into flour). I think if I managed to put a basic water wheel together, I’d be pretty popular.

I know thousands of songs. Also, musical instruments like the saxaphone haven’t been invented yet.

I guess I could make a name as a mathematician, though that’d depend where the fuck I’m snapped to.

I’d like to warn the Incas to not trust anyone with white skin, kill them all on sight and NEVER let any of them get within 100km of Potosi, but I don’t think I’d be anywhere near the Andes either way.

I’m on the Gregorian calendar, 650 years ago is the year 1375. I’m in North Carolina, so if I were to snap back in time at my present location I would be a blue eyed white guy in pre-contact North America. And while I think I’m an above average candidate for the Connecticut Yankee in King Arthur’s Court scenario I’m not realistically able to start “from scratch.” I’d probably make it the summer on forage and my own body fat. I don’t picture encountering the natives going particularly well, for me or them. I’m not sick and I’m vaccinated against a lot of shit but watch I’ll give them 6 centuries worth of influenza updates.

I don’t think it would help that much being plunked down in 14th century England; we’re talking Geoffrey Chaucer’s lifetime here, to them I’d sound insane. Modern English is a few hundred years off. If they didn’t trepan me to let the demons out of my skull and I didn’t die of smallpox, I’d try to invent the electric motor 500 years early and be burned for heresy or some shit.

This is something I often wonder about, what could one person even do with all of today’s common knowledge? You can’t very well just invent the printing press and have the same impact as Gutenberg - you need something what the few people who can read would, and most people can’t translate the bible from Latin into renaissance German and/or don’t know enough about the catholic church to write scathing remarks on it like Luther.

You can write and read - that’s something. Maybe more importantly, you can do math with arabic numerals - boom, easy accounting job. With a bit higher education, you may even just invent calculus once more. You know how long it took for people to figure out you can put pi on the number line? Proving all the formulas in your head is the hard stuff, but you have a head start just by knowing them. We all clown on the wormhole explanation with the paper, but it does prove Euclid wrong 400 years early.

Ah, and you can just become a medical genius by using soap and bandages - “do no harm” is better than most.