Will Thalhiemer put together a report on the positive impact of spaced repetition on retention.

So what is the spacing effect? It is the finding that spaced repetitions produce more
learning—better long-term retention—than repetitions that are not spaced. It is also the
finding that longer spacings tend to produce more long-term retention than shorter
spacings (up to a point where even longer spacings are sometimes counterproductive).

“So what is the spacing effect? It is the finding that spaced repetitions produce more learning—better long-term retention—than repetitions that are not spaced.  It is also the finding that longer spacings tend to produce more long-term retention than shorter spacings (up to a point where even longer spacings are sometimes counterproductive).”

.CC Attribution  NASA Goddard Photo and Video http://www.fotopedia.com/items/flickr-5096879854

CC Attribution NASA Goddard Photo and Video http://www.fotopedia.com/items/flickr-5096879854
.

“Spaced repetitions need not be verbatim repetitions. Repetitions of learning points can include the following:

  1. Verbatim repetitions.
  2. Paraphrased repetitions (changing the wording slightly).
  3. Stories, examples, demonstrations, illustrations, metaphors,and other ways of providing context and example.
  4. Testing, practice, exercises, simulations, case studies, role plays, and other forms of retrieval practice.
  5. Discussions, debate, argumentation, dialogue, collaboration, and other forms of collective learning.
  6. Repetitions can also be delivered to different perceptual modalities (visual, auditory, olfactory, kinesthetic) and through different learning media (text, audio, video, computer, internet, classroom, etc.).

“Regardless of the way repetitions are manifested, if two or more presentations of the same learning point are repeated with some sort of time delay between them, they are likely to produce the spacing effect.”

See more from Will at http://www.willatworklearning.com/