Research School Network: Using Spaced Practice in Inform Curriculum Design Many curriculums now incorporate spaced practice, but how much time exactly should be left between studying and testing?

Engaging with curriculum design means handling multiple threads at once and weaving these together to create a perfect tapestry – one that utilises intricate detail to create a beguiling yet functional design. In order for this curriculum tapestry to withstand the footsteps of time, each thread must be selected with care. Educational research pinpoints spaced practice as a key strand in this endeavour.

Cepeda et al’s paper ​‘Spacing Effects in Learning: A Temporal Ridgeline of Optimal Retention’ provides an interesting perspective of the wealth of research that has taken place on spaced practice over the last 100 years. The spacing effect refers to the practice of placing a temporal gap between study sessions before restudying or retesting; this increases the likelihood of information being remembered in the future. Interestingly, Cepeda explains that most of the research on spaced practice (alternatively known as distributed practice or spacing) has been focused on ​‘the effects of the gap between exposures on later memory’ but in this paper he turns our attention to how ​‘an understanding of how the gap between two exposures affects subsequent forgetting is fundamentally important if one wishes to temporally structure learning events in a rational manner’.

Cepeda recommends that spaced practice ​‘should involve multiple periods of study devoted to the same material, separated by some variable time gap, with a final memory test administered after an additional retention interval measured from the second exposure.’ There have been many studies that explore the outcomes of this spacing practice, and, overall, the results strongly indicate that leaving no gap results in a worse final test result (for a test taken some time later) compared to leaving even just a short gap. However, despite the overwhelming evidence, the world of education still seems to be lagging behind in terms of putting spacing into practice.

Cepeda posits that one possible reason for this lack of engagement may be the lack of clarity about exactly how much time should be set aside between study sessions and the final test in order to engender the best possible results. Here, it is useful to refer to Cepeda’s use of the terms ​‘gap’ and ​‘retention interval’ (RI). ​‘Gap’ refers to the time between the first studying of material and subsequent restudy of the same material. ​‘RI’, on the other hand, refers to the time between the last restudy session and the final test on that material (see diagram below).

For the research in this paper, Cepeda and his colleagues’ aim was to investigate beyond the principle that leaving time between study and testing results in better test performance and delve further into questioning how different timings may affect these results. This work was based on the premise that when planning for spaced practice, attention should be given not just to ensuring there are gaps and then a retention interval but rather how to maximise results through using the optimal ratio between the two. Their trials involved more than 1,350 individuals who were all taught a set of facts and then given a review before being tested on the same material. The various trials incorporated differing ratios of gaps to RIs. 

Ideally, this research would have led to a golden ratio of gap to RI time in order to ensure maximum performance in final tests at a later date. However, as Cepeda notes ​‘for practical purposes, the results reveal a sobering fact […] if you want to know the optimal distribution of your study time, you need to decide how long you wish to remember something.’ However, what has become evident is that ​‘if a person wishes to retain information for several years, a delayed review of at least several months seems likely to produce a highly favourable return on the time investment.’ Furthermore, the costs of using a gap time that is shorter than what is optimal far outweighs the cost of using too long a gap.

Summary and Implications for Curriculum Design

• As a general rule, a longer temporal gap between study sessions of the same material increases the level of future recall.

• Correspondingly, too little spacing between study sessions is quite detrimental to retention whilst too much time between study session leads to only small decreases in later recall.

• Planning cumulative assessments is one of the most effective elements of curriculum design in terms of promoting durable memory for the material being taught. Likewise, systematic quizzes that interleave topics can also be extremely beneficial.
  

• Testing with feedback is better than restudy alone. An effective way of using testing with feedback for spaced practice is to delay providing feedback from a test or exam. Ideally, the feedback should take the form of frequently re-presenting questions that students found challenging in a test and asking them to answer before providing feedback to ensure accuracy.
  
  Finally, the goal of any curriculum should be to enable students to have access to the bodies of knowledge that are part of society’s ​‘big conversations’, and to be able to apply this knowledge to contexts far beyond any single period of examinations alone. This is why, despite the counterintuitive experience of short gaps between study and testing leading to better immediate test performance, spaced practice needs to be an integral part of any curriculum design.