I+1
From RevTK
i+1 is a principle of language learning which involves quantifiying what is known and adding a small amount of additional information in order to ease into understanding the additional information. In this principle, "i" refers to what is known and "+1" refers to what is unknown. The concept of i+1 is derived from Stephen Krashen's input hypothesis, but is often applied to spaced retrieval software to refer to new information on a given card, such as a single new vocabulary word per card. When used in this fashion, it may be written as i+N. The shared Anki plugin, Japanese Morphology, allows Anki users to keep track of known vocabulary words in their decks and sort cards by the number of unknowns with the iPlusN feature.
