Duolingo is my FAVORITE LANGUAGE APP! The only thing that I think needs improved is the fact many people are interested in Sign Language and we don't have it! Some people are worried about how we would learn it in Duolingo, but I think that flash cards would work pretty fine. I really hope you add sign language!
This is also by Duolingo: https://tinycards.duolingo.com/decks/194f09ec-e304-4045-b53a-4f2d50c8cfee
I'm just taking a looking at these, and several of the cards are extremely misleading. For example, it's impossible to tell from these that K and P have the same hand shape, several of the signs are rotated from how the recipient would see them, and G looks like a pointing finger instead of having a gap between the thumb and finger like Q. The non-initial variant of X is also absent.
It seems as if someone has simply taken David Rakowski's Gallaudet font, which IMO is not useful for teaching the ASL manual alphabet, and simply created derivative pictograms in Duolingo's design language without any adaptation for the intended purpose.
I would absolutely love for this to happen. However, it would require whole new mechanisms for video content, as you can't really teach ASL grammar with words or static pictures. I'm also not really sure how input for English -> ASL translation exercises would work, though I'm sure something innovative could be figured out.
If this is something Duolingo wants to undertake, there's something I'd absolutely beg of them. If they do this, I'm sure they're going to want to hire an expert in ASL to get started, and if this happens, please, please, please hire a Deaf linguist or language instructor who signs ASL as their first language. Hearing translators and self-professed hearing "experts" on ASL are often not fluent and don't fully understand the nuances of the language, which is depressing when you consider how often they are given jobs over vastly more qualified Deaf signers.
It's a good idea, I'd love to learn sign language. I think I'd take classes though, I don't think I'd be able to learn Duolingo-style, but I'm sure others could. I think it's a shame that there's so many different versions, and most English-speaking countries are separated.