Electricity
Occasionally scientific understandings change, and our children learn different facts than we did. The way that math is taught seems to me, as a parent, to constantly change so that I no longer understand how you’re mean to t learn division anymore.

Historical fact tends not to change too often, but cultural understandings, how things are taught, and who is given credit does sometimes. Benjamin Franklin did not, in fact, invent electricity. It is much more accurate to say that Nikolas Tesla, Michael Faraday, James Maxwell, and Thomas Edison all played much bigger roles.