One thing to keep in mind is that the translations are all English to another language - not the other direction. And for English, French, Spanish, German, Italian and Portuguese, the translation goes both to and from English. No fuss, no muss, no downloading required here. Thanks a lot. Working with the deaf, you'll need to learn both fingerspelling and sign language.
Fingerspelling is just what it sounds like.
Each letter has a hand symbol, and assuming you're a decent speller, you can hand spell out words. The site also has a nifty Fingerspelling Converter, clickable from the homepage. Just enter a word, and the converter will generate an automated sequence of hand movements that spell it out. Not so fast. Take the Fingerspelling Quiz, also clickable off the homepage.