Conjuctions 'aber' and 'Sondern': additional instruction
The conjunctions "aber" and "Sondern" are both described as "but".
For clarity, the course should note that 'aber' is the form for disregarding the previous statement as influencing the following: "I got paid, but I had to pay off my loan and am still broke." 'Sondern' is the form for correcting a negative statement: "I'm not rich, but instead I am poor."
These are "but still" (or "and yet") and "but rather" (or "instead").
A lot of the German lesson material is brief or disorganized. I feel like the course has gotten some recent development and lacks polish on that just yet.
Haha no worries. Well, just to make myself abundantly clear for anyone else reading (and so you can make sure you only misunderstood me the one time :P);
When you are told your answer is wrong, when you know it is correct; there should be a button with either a small flag or a button that simply says "Report" on it that you can press or click on, which will then give you a number of options to select from to report an issue with the sentence.
One of these options should read something like "My answer is correct". After selecting and submitting the report, a small message should appear - thanking you for reporting and possibly also stating that a moderator will check your report and update the sentence accordingly; and I can say from experience that when a suggestion of yours is accepted as a correct sentence, one of the duolingo moderators will email you letting you know.
I know quite a few people on duolingo just report their answers as correct whenever they think they might not have been wrong, because reporting your answer as correct doesn't guarantee it will be accepted as correct the next time you do it, or even ever at all. It simply means a moderator will look at it and review the sentence.
Whilst I wouldn't try to dissuade people from that practice, I wouldn't recommend it, not because what I said isn't true, but just because it creates a lot of work for the moderators and I read somewhere recently that they have a serious backlog already as is.
However! Reporting is a large part of what makes duolingo as good as it is. Duolingo is a nonprofit, and the user interaction and feedback help improve it for everyone.