You jump in and begin seeing and hearing simple words in the foreign language and start translating, learning nouns, verbs, and other parts of speech without memorizing declensions and without tears.
For a mind-boggling explanation of what's going on, watch von Ahn's presentation on massive-scale online collaboration at http://bit.ly/12VNTVv.
For translating on the fly, there's Google Inc.'s Google Translate, a free app with versions for most devices, though the Android iteration has the most features. The app works in scores of languages including Azerbaijani, Estonian, Icelandic, Persian, Russian, and Urdu.
With patience, you could use Google Translate to "converse" with someone even if neither of you knew the other's language. Type or speak a phrase and tap for the translation. The Android version has a "conversation mode" that displays each side of a discussion in cartoon-voice bubbles.
Lingualia - Language Course is a free new app from Lingualia SL Education and is for iPhone and Web users, though an Android version is in the works. After you sign up, Lingualia asks whether you want to learn Spanish or English. Another tap and the app takes you to the first lesson. Hola! You are off and running with a dialogue between Juan and Mario.
Play and repeat phrases, then use "flash cards" on subsequent screens to begin fixing the words and phonetics into your brain. Lessons end with "checkpoints," otherwise known as tests. The "adaptive learning" software is designed to uncover gaps in your progress and fill them in.
Social features allow you to follow other students and post on a wall. Promotional material says the app has 200 lessons in both English and Spanish and 3,000 vocabulary flash cards.
Contact Reid Kanaley at 215-854-5114, email@example.com, or @ReidKan on Twitter.