"These girls are pretty."
Translation:Diese Mädchen sind schön.
So "süß" is "cute" and "schön" is "pretty", and they must not be confused. OK, Duo, I'll try to remember this.
Because Mädchen is plural here.
dieses Mädchen (with neuter singular dieses) = this girl
diese Mädchen (with plural diese) = these girls
That just means "nice" and generally refers to character, whereas "pretty" refers to appearance.
Can you provide some context?
What did you see where that word came up? Please provide the entire sentence.
In this sentence, Mädchen is plural.
(And note that madchen, with lowercase m and with a without dots, is not a German word at all.)
Why "Die Mädchen sind schön." is not accepted? According to https://www.duolingo.com/skill/de/Possessive-Pronouns/tips-and-notes "That means, der, die and das can also mean "that (one)" or "this (one)" depending on the gender of the respective noun, and "die" (plural) can mean "these" or "those.""
It's not one of the accepted alternatives the Pearson editors provided for this sentence as part of their course.
You can report it if you'd like -- I agree that it should be accepted. (Though I would prefer Diese Mädchen sind schön. in this case.)
Both should be possible (see the other comments on this page for why die is currently not accepted). diese is more explicitly "these", while die is basically "those" but is also often used for "these".