> Those both seem much easier to me than what I usually struggle with: Transported back to a pre-industrial time, is any of my technological knowledge or unders

> Those both seem much easier to me than what I usually struggle with: Transported back to a pre-industrial time, is any of my technological knowledge or understanding even remotely useful? That's an interesting topic, and there's a whole community that is interested in this. Mostly for historical and educational reasons. Surprisingly, there are quite a few things you can reasonably do. You will never be able to build a useful internal combustion engine starting in a pre-industrial time. But you'll be able to introduce the positional decimal notation (took 4000 years to invent!), double-entry bookkeeping, paper making, printing press. If you know a bit of technology, then you can create water plumbing (just avoid lead), and at least some metalworking.