I'm having trouble finding sentences that haven't already been translated. Is there a way to find sentences that still need translation?
I am having the same problem. If I look at material even just a few days old, it is often already completely translated. Remarkably, I've recently started looking at material that's very much older (sometimes as much as three months) and found that often it hasn't been completely translated yet. I'm not sure why that is, and I suspect it won't stay that way, but, for now at least, some of the really old material still needs translation work too.
Was it always this way? I'm sure when I started Duolingo you could translate any article and then it would show you the way other had people had done it, but maybe I'm wrong... Either way, I think it's pretty pointless the way it is now. There's no challenge if your only task is to better someone else's translation, rather than taking the time to read and try to understand the text by yourself.
No, you're quite correct toomanysophies. It used to be that you could try translating any sentences in a selection and it was much easier to find selections to translate. Here: http://duolingo.com/#/comment/65077?from_email=comment is another group with the same concerns.