> In school in Belgium, we learned that Oceania is the continent and not Australia. So for us, would Australia then be the largest island after all?
No, whether you call the continent “Australia” or “Oceania”, the land mass that makes up the entirety of the mainland of it is, ipso facto, not an island, and neither is the country occupying the entirety of that landmass and some adjacent islands (though, of course, it contains several islands.)
> In school in Belgium, we learned that Oceania is the continent and not Australia. So for us, would Australia then be the largest island after all?
How weird. (So it's not only Chilean schools that are idiosyncratic in this regard.) To the rest of us, the actual continent -- you know, the biggest contiguous landmass in the region -- is called Australia. Maybe you're just translating Erdteil (Ger; whatever the corresponding concept is in French or Flemish) to the English "continent", and mistranslating too literally? In English "continent" is the land mass, which is definitely Australia. Oceania, as a whole "Erdteil", is more than a continent; it's the sum of the continent of Australia and a whole bunch of islands. (Possibly most of them situated on the same continental shelf? Or not, Idunno.)
French:
> On retrouve ainsi certains systèmes de continents qui considèrent l'Europe et l'Asie comme deux continents, alors que l'Eurasie ne forme qu'une étendue de terre. -- https://fr.wikipedia.org/wiki/Continent
If stuff that is just one actual literal continent can be called two "Erdteile" since forever, another "Erdteil" can consist of a continent plus some other stuff.
West Flemish:
> De meiste eiland'n in de Stiln Oceoan vormn t'hope mè 't continent Australië e weirelddeil die Oceanië wordt genoemd. -- https://vls.wikipedia.org/wiki/Continent
Oceania is not Australia. After the Wikipedia article: "Oceania is a geographical region which includes Australasia, Melanesia, Micronesia, and Polynesia".
In English, Australia is just Australia. The Australian continent includes the Australian mainland, New Guinea and several islands within Australian or Indonesian jurisdiction.
Oceania is this designation of convenience that excludes islands that are non-Continental and would otherwise be lumped in with Asia, and in addition to Australia there are three groupings of island territories which are ethnically classified as Melanesia, Micronesia and Polynesia.
Melanesia includes New Guinea (remember, part of the Australian continent, separated from the country by a strait), and running east goes to Nauru, southeast to Fiji, and then west to New Caledonia which is essentially one of the highest altitude masses of the mostly submerged continent of Zealandia (the other land masses being New Zealand and a few islands belonging to the country of Australia). Melanesia also includes the Solomon Islands and Vanuatu.
Micronesia is a region that from Palau runs east through the Federated States or Micronesia to Kiribati, northwest to the Mariana Islands (including Guam) and back down to Palau and is mostly in the Northern Pacific.
Polynesia forms a near-triangle often referred to as the Polynesian Triangle with New Zealand in the Southern corner, Hawai’i in the Northern corner and Easter Island in the Eastern corner. There are too many island groups here for me to want to list them all, but this is essentially where Polynesian peoples settled.
Which brings us back to Oceania. There’s all these islands people live that if you squint your eyes a little look like they’re close enough to Australia. Why not just group them all together and call them a continent? And from what I’ve gathered that’s exactly what a lot of countries have done for a while or started to do. Continents are basically arbitrary BS anyway, good BS that serves a useful purpose colloquially but still BS; and it looks like to me like it’s just a way of keeping the list of “major regions” shorter than it otherwise would be because between Australia also being a country and all of these archipelagos spread out across the Pacific being both low population and underdeveloped, nobody wants to append them to a list of supposed “continents” as separate entities, so Oceania it is.
And if you did that, what about India? Arabia? Madagascar? The western portion of North America basically divided by the Rockies? This would start to get political after a while.
So eh, Australia is a continent in English, but Oceania is a region that includes Australia. Whether the continent of “Australia” includes the obvious portions like New Guinea, well, not when I was in school, but I don’t think that matters.
No, whether you call the continent “Australia” or “Oceania”, the land mass that makes up the entirety of the mainland of it is, ipso facto, not an island, and neither is the country occupying the entirety of that landmass and some adjacent islands (though, of course, it contains several islands.)