"Sie sind ein Mädchen."
Why is "Sie sind ein Mädchen." a correct translation of "you are a girl." ? I understand that it's technically grammatically correct, but it doesn't really make sense to say you(plural) are a girl.
Sie is formal you and Sie/sie uses the infinitive. This means you're saying "You(formal) are a girl" although it doesn't make much sense as kids are usually never spoken to formally because others kids are their age and adults usually speak to children informally.
Yes, in this case Sie is a formal "you", which you would use with someone you don't know.
blackwind: Beginning (I believe in Gymansium) students and teachers both use the formal you. So it wouldn't be that weird for a high school teacher to say to a female student "you are a girl".
duodanny: I was thinking more like of 5 year olds and what not but I suppose that makes sense.
Pupils are spoken to formally in school at age 15 or 16. So it actually should be "Sie sind eine junge Dame." I would say "Du" to a younger girl of a royal family too, not "Sie". But well, this is Duolingo. The sentence is gramatically correct.