Is Duolingo using some kind of spaced repetition algorithm? ( http://en.wikipedia.org/wiki/Spaced_repetition )
Sometimes it doesn't feel like it when I get asked again and again easy words that I never fail, but almost never get asked those really hard to remember words.
I'm still having the same issues as described in my original post.
There are these few sentences I get constantly wrong yet Duolingo asks them very rarely. And then there are a couple of sentences that I'm asked almost daily and never answer wrong. I love Duolingo a lot but the spaced repetition implementation might need some improvement. Or maybe it's just an issue with my account?
For contrast I use Anki regularly and it's algorithm works flawlessly: failed sentences are repeated more often.