The term distributed- practice effect refers to the finding that distributing learning over time (either within a single study session or across ses- sions) typically benefits long-term retention more than does massing learning opportunities back-to-back or in relatively close succession. (35)
Spaced practice (1 day or 30 days) was superior to massed practice (0 days), and the benefit was greater following a longer lag (30 days) than a shorter lag (1 day). (36)
Cepeda et al. (2006) reviewed 254 studies involving more than 14,000 participants altogether; overall, students recalled more after spaced study (47%) than after massed study (37%). (36)
Cepeda et al. (2006) noted that most studies have used rela- tively short intervals (less than 1 day), whereas we would expect the typical interval between educational learning opportunities (e.g., lecture and studying) to be longer. Recall that the classic investigation by Bahrick (1979) showed a larger distributed-practice effect with 30-day lags between sessions than with 1-day lags (Fig. 10); Cepeda et al. (2006) noted that “every study examined here with a retention inter- val longer than 1 month demonstrated a benefit from distribution of learning across weeks or months” (p. 370; “retention interval” here refers to the time between the last study oppor- tunity and the final test). (37)
However, the answer is not as simple as “longer lags are better”—the answer depends on how long the learner wants to retain information. (37)
distributed-practice effects are large for free recall but are smaller (or even nonexistent) for tasks that are very complex, such as airplane control (Donovan & Rados- evich, 1999). (38)
Several obstacles may arise when implementing distributed practice in the classroom. (38)
how students naturally study. Michael (1991) used the term procrastination scallop to describe the typical study pattern—namely, that time spent studying increases as an exam approaches. (39)
students may need some training and some convincing that distributed practice is a good way to learn and retain information. Simply experiencing the distributed-practice effect may not always be sufficient, but a demonstration paired with instruction about the effect may be more convincing to students (e.g., Balch, 2006). (39)
we rate distributed practice as hav- ing high utility: It works across students of different ages, with a wide variety of materials, on the majority of standard labora- tory measures, and over long delays. (39)
Dunlosky, et al “Improving Students’ Learning with Effective Learning Techniques” Psychological Science in the Public Interest 14.1 (2013): 4-58.