Phone unlock screen to learn language

Say you want to learn chinese. When you pull out your phone, instead of the same old boring lock screen, there is a word or character, and multiple possible meanings. You drag the word to the correct meaning, you unlock the screen. There's also a "give up" option if you just want to unlock the phone.

The program keeps track of which words you have mastered, and every so often a new lock screen comes up with a word you haven't learned yet. It simply shows you the meaning, and the only option is "ok", to acknowledge you have read it. This word will now be one of the possible random words that will appear.

If the phone is ringing and you want to unlock the screen right away, those options are of course also available.