This article discusses inventions that we don’t realize are very recent. So the time they were invented may be an invertible fact to many people. The article is on Cracked.com so the claims should be verified carefully (although sometimes I feel that they do more fact checking than much of the official media.) Highlights include the doorknob (invented in 1878. I would have guessed last thousand years, but certainly not that recently). One on the list, timzonzes struck me as very obviously recent, but that may be because I’ve read a bit about the history of railroads. I also don’t think the example of “nationalism” is quite correct, or at least, they are drastically oversimplifying in that entry. But the overall thrust might do what you want.
This article discusses inventions that we don’t realize are very recent. So the time they were invented may be an invertible fact to many people. The article is on Cracked.com so the claims should be verified carefully (although sometimes I feel that they do more fact checking than much of the official media.) Highlights include the doorknob (invented in 1878. I would have guessed last thousand years, but certainly not that recently). One on the list, timzonzes struck me as very obviously recent, but that may be because I’ve read a bit about the history of railroads. I also don’t think the example of “nationalism” is quite correct, or at least, they are drastically oversimplifying in that entry. But the overall thrust might do what you want.