Spaced repetition is a learning technique that incorporates increasing intervals of time between subsequent review of previously learned material in order to exploit the psychological spacing 

Simulation of SRS vs

Simulation of SRS vs. Traditional Review

effect. Alternative names includespaced rehearsalexpanding rehearsalgraduated intervalsrepetition spacingrepetition schedulingspaced retrieval and expanded retrieval.[1]

Although the principle is useful in many contexts, spaced repetition is commonly applied in contexts in which a learner must acquire a large number of items and retain them indefinitely in memory. It is therefore well suited for the problem of vocabulary acquisition in the course of second language learning, due to the size of the target language's inventory of open-class words.


Most spaced repetition software (SRS) programs are modeled after the manual style of learning with flashcards: items to memorize are entered into the program as question-answer pairs. When a pair is due to be reviewed, the question is displayed on screen, and the user must attempt to answer. After answering, the user manually reveals the answer and then tells the program (subjectively) how difficult answering was. The program schedules pairs based on spaced repetition algorithms. Without a program, the user has to schedule flashcards; this is time-intensive and limits users to simple algorithms like the Leitner system.

Further refinements with regard to software:

  • Questions and/or answers can be a sound-file to train recognition of spoken words.
  • Automatic generation of pairs (e.g. for vocabulary, it is useful to generate three question-pairs: written foreign word, itspronunciation and its meaning—but data only has to be entered once.
  • Additional information retrieved automatically is available, such as example sentences containing a word.
  • Opportunities to combine spaced repetition with online community functions, e.g. sharing courses.

Some implementations:

 The spacing effect is the finding that spaced repetition generally leads to stronger memories than massed repetition. One explanation of this effect is that we pay more attention to material that we haven’t seen for some time, and a second explanation is that spaced repetition embeds an item in our minds across a larger number of contexts. The spacing effect is just one small part of the science behind how Memrise tries to make learning as easy as possible!

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