Improving grammar feedback
What happens after a user checks the option "My answer should be accepted"? Is it included in the system automatically as a proper translation? My guess is that it will, after a determined number of people submit that answer to Duolingo, in the same way that translations progress towards completion.
If that is so, then I think that is a pretty good system. But here's my objection. If you phrase it like that (SHOULD be accepted), I'm convinced a lot of people won't be confident enough to submit their answer, because after all, they're most likely learning the language and therefore aren't 100% sure about it. Sure, they can always initiate a discussion and clarify their doubts, but then they don't have a simple way of submitting this feedeback; their only option is to submit it if they refresh that lesson and happen to stumble uppon that particular sentence. Not to mention they still have to memorize what the experts said in that discussion.
By the way, I'm not speculating, here's a discussion where another user (Barbeito) gave voice to these concerns) - http://duolingo.com/#/comment/127346?from_email=comment
My point is, therefore, that the wording of controls must be carefullt pondered, and that "I THINK my answer should be accepted" is probably a more suitable choice of words, one that might have a significant influence in the amount of grammar feedback users will provide Duolingo. Naturally, that would apply to all other checkbox labels.
If this still won't bring down the number of gramamr errors across Duolingo, then perhaps a similar system to that of the translations' page, with user voting, would be put in place, to achieve more accurate results. That would optimize the error-removing process, as users coming to the discussion through the forum, rather than through lessons, would be able to participate in the corrections. Also, not the only one who thought about this issue, see this discussion beginned by Hohenems - http://duolingo.com/#/comment/132957
By the way, I just came across one sentence with two given translations, one of which was wrong. The checkbox "the given answer has a mistake" won't let me specify, of course. Not sure how I would hanlde this, though. I suppose that in the "voting system" I described, Duolingo's translations would be subjected to user voting also.
Still another instance where the system fails to allow the user to correct it: I'm doing a certain lesson for the second time, and I've noticed that Duolingo only shows a second possible answer if you haven't given it as your answer. That means that if a secondary answer is wrong, you will probably never see it and correct the system. In other words, you have to type that wrong secondary answer for the system to acknowledge it. But if you typed it, you think it is correct. See the conundrum? Probably not, this is quite confusing. And now of course I don't have a way to inform the system that my answer is wrong.