I probably should have mentioned a few more details in my first answer (in order to confuse you even more...): In more informal settings, in which neither of the people involved is a professional teacher, and you just want to say that one of them is casually teaching the other person how to do something (no structured class / no professional teaching skills required), we can use the term "å lære noen noe" instead of "å undervise". In that case, the person who has a skill or some knowledge about something "lærer bort noe til en annen" (literal translation: teaches away something to somebody else). Some examples: - Han ville lære datteren sin å sykle - Hun lærer kjæresten sin å spille tennis. - Han lærte lillesøsteren sin å knyte skolissene. - De bestemte seg for å gjøre en språkutveksling: Han skulle lære henne å snakke polsk, mens hun skulle lære ham å snakke norsk. - De to guttene hjalp hverandre med leksene: Per lærte Knut hvordan man bøyer tyske verb, mens Knut lærte Per å regne ut areal og omkrets av en sirkel. Let me know if any of this was unclear, and I´ll try to explain in further detail.

Yes, this can be a little confusing when translating from English. Hopefully these translations will make it clearer: I am a teacher = Jeg er lærer I teach Polish / I´m teaching Polish = Jeg underviser i polsk I learn Norwegian / I´m learning Norwegian = Jeg lærer norsk I study Norwegian / I´m studying Norwegian = Jeg studerer norsk So, the noun "(a) teacher" = "(en) lærer", but the verb "to teach" = "å undervise". The verb "to learn" = "å lære". Læreren er den som underviser. Studenten er den som lærer.