"I am an adult, I do not go to school anymore."
Translation:Jestem dorosła, nie chodzę już do szkoły.
Ok, sorry. Trochę dzisiaj "naspamowałam", ale w kilku miejscach nie byłam pewna, czy faktycznie warto dane tłumaczenie dodawać. Z doświadczenia - w innych kursach jest tyle requestów o korektę, że często dyskusja rozwija się w ciekawą stronę zanim ktoś interweniuje. Zresztą pewnie wiesz jak to jest. :)
But the instrumental form of "dorosły" is "dorosłym." "Dorosła" is the feminine adjective form of the word. Is this a special case in which you use the adjective "dorosły" to describe yourself as an adult rather than describing the subject of the sentence by using the instrumental form of the noun "dorosły?"
Well, this is firstly an adjective, that just can potentially work as a noun, and here it does indeed describe 'me', just like any adjective (short/tall/intelligent) would.
As for saying "Jestem dorosłym/dorosłą"... maybe technically it isn't wrong, but sounds very strange to me.
I wasn't aware. I knew that "dorosły" was both a noun and adjective and you can use either to describe yourself as an adult, but in this sentence, it says "I am an adult," meaning that its using the noun form and up to this point I've trained my mind to using the instrumental whenever the subject is described by means of a noun.
However if using the adjective form of the word is the more natural and common way that native Poles say it I really cannot argue. Thank you for the response.