One of the new features in Keep Your Word 2 (our vocabulary and flashcards trainer for Mac and iPhone) is the implementation of a spaced repetition algorithm to select the words that will be part of a study session.
Until now, when you clicked the “Flash Cards” button, Keep Your Word randomly selected a given amount of words (configurable in the app’s preferences).
You can still do that, but now you can also activate another way of selecting words, based on a spaced repetition algorithm. According to Wikipedia, Spaced repetition is a learning technique that incorporates increasing intervals of time between subsequent review of previously learned material; this exploits the psychological spacing effect.
The actual algorithm implemented in Keep Your Word is the Leitner System. Basically, we separate the cards in five different groups, according to how well we think you know them. These five groups are mapped to the “progress” slider.
That way, you can fine tune the algorithm, and move up or down any word no matter the result of our calculations.
Obviously, you have to help us while you are studying. When you review the flashcards, you can mark a word as “known” or as “not known”. When reviewing any of the other exercise modes, we mark the words are known/unknown automatically.