That was the first case of something my child learning contradicting my own outdated education.
The funny thing is that it is not like this is some new discovery or new knowledge -- Webster's 1913 dictionary has five oceans: "Ocean: 2. One of the large bodies of water into which the great ocean is regarded as divided, as the Atlantic, Pacific, Indian, Arctic and Antarctic oceans." https://www.websters1913.com/words/Ocean So you get to feel like you have a more up-to-date education than your grand parents, your kids feel like they have a more up-to-date education than you, and it all is just a cycle of fashion :-P