diario is also diary which you did not accept. I have a book entitled: Diario de Ana Frank
Diario is better daily newspaper (día), periodico is better magazine (comes periodical), as I know.
I am spanish and I can tell you that in Spain we use Periodico for newspapers, Diario is most commonly used as diary, which for some reason was not accepted as an answer (probably because this course was created by southamericans who use diario meaning newspaper).
Duolingo definitely favors South American Spanish.
Their omission of the vosotros conjugations is evidence of this
I agree with roosky "papers" were accepted in all previous exercises as "newspapers" and is a very common English and American abbreviation for newspaper. Much as I love DL for the great and FREEE language tuition they supply, this lack of standards throughout the entire course is irritating and is as if different persons or algorithms are used at different points throughout the course for marking answers. Its only a small thing but annoying.
We still love love duolingo though! Diary was not accepted for me. FREE lesson learned!
Please correct this exercise... In Spain we say diario for diary and that should certainly be accepted as a correct answer... Spanish in Spain: Revista - magazine, Periódico - newspaper, Diario - diary.