When I first saw the Portuguese sentence and translated it into English in mind, the first word that came up was "around". I don't know a word-for-word translation for "por aí", maybe "by there"? However, the meaning of "por aí" is "with no destination, randomly":
— "Where have you been?"
— "Por aí..." ("I've been going around...").
So, the whole expression is translated this way.
"Eu dirijo por aí" = "I drive with no destination"
"Eu caminho por aí" = "I walk around"
I really think that's a tough time for all!! I've come across some hard moments in other languages through here too =/ In this case, what I do is to write down these slangs (or different uses of the word) just in case I need it later or just to learn a new word in a context... But surely, before that, I lose my heart :(
One of the things I've liked about Duolingo so far is that often there are multiple examples of a particular point of grammar or vocabulary. The repetition really helps, the same way it does in a class where the instructor asks for variations around a common grammatical topic. "I am..." a son, father, brother, student, human, etc.. On the other hand, I do think that language programs need to make sure the foundations are solid before building extensions that the foundations can't support. In the end though, yes, a dedicated student should make use of any material that isn't blatantly incorrect. Occasional frustration makes for a more determined learner! ^_^
But I think they do this kind of as a challenge. Usually these kinds of algorithms will make the exercises ever so harder when they see that you're statistically doing above average. As soon as they detect you consistently failing on that part they should turn the difficulty down ever so slowly. Besides, as you said, a little frustration makes a more determined learner. And to that I'd add that sometimes the learner becomes lazy guessing the answer because it looks a little like the answer I gave before and when that happens we defeat the purpose because instead of thinking about what the answer should be and why we're doing it mechanistically.
one word : boring ! That's the 3rd time in a row that i fail this one particular lesson... because of translations so meaningless or not accurate (and of course I see that the responsibility is mine because I am the one making the mistakes.... but i really think duo does not help here and in this case I am not encouraged to go on.... to me, frustration does not make me a more determined learner but a more frustrated almost quiter... i do not find joy in learning that way, and learning without joy, what's the point ?
That was my "I'm fed up and I need support" moment :)