Ele é moreno.
Surely there are lots of people who are running into problems like this, but the sentence above was given to me to translate to English. The word "moreno" was highlighted, as it was a new word. Clicking it gave me 3 usages/translations: "dark", "brown", and "dark person". I typed in my translation as "he is dark." Duolingo found this wrong... The answer they were looking for is "he is tan". I'm not arguing that duolingo is wrong, but why would it give me a translation where the word "moreno" is contextual, when I've never even seen the word before? Very frustrating. I did not realize that they meant "tan" instead of "dark". Also, my other issue in this sense is how vague the statement is. Accepting the fact that Duolingo may be avoiding racial statements, there are light-skinned and dark-skinned Brazillians. I don't think Duolingo is attempting to side-step racial statements, though... 3 questions previous to this one was to translate "A mulher é prato" or "the woman is black." Anyway, a "tan" man and a "dark" man are not necessarily the same thing, but there were no context clues to indicate which would have been the correct answer. This is not the first time that I've run into this sort of thing, either, although this is the only example that I can think of.
Actually, "he is black" we would say "ele é ❤❤❤❤❤" ("ele é preto" sounds rude). But "he is tan" we say "ele é bronzeado". "moreno" is usually connected to "brunet, brown". But, if we say "ele está moreno" it means he sunbathed for a long time and now his skin is tanned... but you'll face other examples where you'll llse hearts for having no clues in the mouseover :(, especially involving expressions...
I share your frustration. This does not happen only in the Brazilian Portuguese course, but also in the French one. But since this is a great and completely free tool, we just have to accept those glitches and try to help them to improve it by sending reports when there is something unnatural or wrong.
Moreno is a complex term. It can be used to refer to a person that is dark-skinned but not black, although the technical term for that here is pardo (http://en.wikipedia.org/wiki/Pardo), it can be used to refer to one's hair color (brunette), and when used with the verb "estar", which gives it a temporary meaning, it can be used when someone is sun tanned (but we have the word bronzeado for that).