Spaced Repetition

The concept, that Spaced Repetition could be used to improve learning has been around since about 1932 [1]. It was first proposed in the book Psychology of Study by Prof. C. A. Mace.

"Perhaps the most important discoveries are those which relate to the appropriate distribution of the periods of study...Acts of revision should be spaced in gradually increasing intervals, roughly intervals of one day, two days, four days, eight days, and so on."

Notable implementiations of Spaced Repetition include Anki or SuperMemo. The extent to which these system can be used has no boundaries. Traditional implementations where used mostly in learning new languages, as seen in the image.

Michael Nielsen is an avid user of spaced repetition techniques and wrote an excellent article about Augmenting Long-term Memory.