Duolingo function idea.
I think it would be awesome to have a ranking system of the users.
For example: if you choose "Spanish ranking" you see a ranking from members in the first place, with the higest spanish level folowed by people with less Spanish skills.
This way, you can challenge yourself with the person above you in the ranking and aim to get a higher ranking or even aim to get in the top 100, top 10, number 1,...?
For privacy reasons you can make an option to "be visible or invisible" in the ranking for each user to choose.
What do you think?
I think it would push people to be more concerned about points/levels than actually learning a language -- something already very much in evidence. ;) How about comparing scores on the proficiency exam, something that attempts to measure language skills, since points and levels can be a poor indicator of one's actual ability.
(I also didn't take it too serious as the absolute level of my skills. Just as a push to keep you going and make it fun.)
I think it will be hard to write code that will decide who is the highest rank: the person who finished the entire tree in 2 weeks (do they already know the language and they are just using Duo as a review? Did they write all the sentences down as they went and kind of cheat their way through as quickly as possible without really learning anything?) as compared to the person who has the most XP (are they doing a lot of review, researching topics in depth outside Duo, and learning the language deeply, or are they bored and killing time by repeating the first couple of lessons over and over while they should be paying attention in class?).