Three-sided flashcard

A flashcard or flash card is a set of cards bearing information, as words or numbers, on either or both sides, used in classroom drills or in private study. One writes a question on a card and an answer overleaf. Flashcards can bear vocabulary, historical dates, formulas or any subject matter that can be learned via a question-and-answer format. Flashcards are widely used as a learning drill to aid memorization by way of spaced repetition.

Flashcards exercise the mental process of active recall: given a prompt (the question), one produces the answer. Beyond the content of cards, which are collected in decks, there is the question of use – how does one use the cards, in particular, how frequently does one review (more finely, how does one schedule review) and how does one react to errors, either complete failures to recall or mistakes? Various systems have been developed, with the main principle being spaced repetition – increasing the review interval whenever a card is recalled correctly and recalling the important information of the subject of study.

Physical flashcards are two-sided; in some context one wishes to correctly produce the opposite side on being presented with either side, such as in foreign language vocabulary; in other context one is content to go in only one direction, such as in producing a poem given its title or incipit (opening). For physical flashcards, one may either use a single card, flipping it according to the direction, or two parallel decks, such as one English-Japanese and one Japanese-English. They have a number of uses that can be very simple or very elaborate for the person to memorize.

There are various systems for using flashcards, many based around the principle of spaced repetition – reviewing information at increasing intervals. Manually managing interval length can add greatly to the overhead of using flashcards: the Leitner system is a simple spaced repetition system designed for paper flashcards, based on a small number of boxes and a simple algorithm, while the SuperMemo algorithms are more complicated, tracking each card individually, and designed for implementation by computer.

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Wikipedia