TouchPaper Problem #7

Last week I was fortunate to attend the first TouchPaper Party. I was in group 7 and we had the following question to unpick:

TouchPaper Problem #7: What is the optimal number of times for a student to (a) read, (b) hear, or (c) say information aloud if they are to retain for 1, 3, & 6 month intervals?

After much discussion, we broke the problem in two. One group looked at what we need to do in the first place to ensure students learn new information and the other group – the one I was in- looked at how we can ensure it stays remembered.

A century of memory research tells us that students forget. Even when the teaching is good and we can say that students have learnt the material, unless we design opportunities for that information to be recalled, it is going to slowly disappear. For information to be retained at the specific intervals identified in the problem (and beyond) we need to revisit the content.

Our discussion led us to 3 main ideas: Spacing, Interleaving and Retrieval and I’ll look at each of them in turn.


Carpenter et al (2012) explain that “… performance on final tests of learning is improved if multiple study sessions are separated—i.e., ‘spaced’ apart— in time rather than massed in immediate succession” and “Studying information across two or more sessions that are separated (i.e., spaced apart or distributed) in time often produces better learning than spending the same amount of time studying the material in a single session.”

This is all very well, but determining the optimal spacing period is difficult. In one study of 1350 individuals and their recall of facts, Cepeda et al (2008) came up with an optimal gap of 1 day for a test in 7 days, 11 days for a test in 35 days, 21 for 70 and 21 for 350 days. The optimal gap being longer depending on the test delay. The results were slightly different for tests of recognition e.g. supplying multiple choice answers. Also, the results would clearly be different if we revisited the content multiple times.

This does seem to go a little way to answering one element of our Touchpaper question and is a helpful reference point even though the optimal gap for a given set of information in a given time frame is very difficult to be precise about. There is simply no formula suggesting that x sessions at gaps of y% of the test interval is the best way to remember.


Suppose you have X, Y and Z to study. Typically, the study of these would be X, X, X, Y, Y, Y, Z, Z, Z. This is ‘blocking’ and is how our curriculum is traditionally laid out. Each topic is mastered before moving on. Interleaving the topics would tend to look like: X,Y, Z, X, Y, Z, X, Y, Z.

Richland, Bjork, Finley & Linn (2005) show us that interleaving is more effective in the long term than studying something in a block. Bjork calls this a ‘desirable difficulty’ because it would seem counter intuitive and is harder to get right. Indeed, students may perform less well in the short term but retain the information over the long term. Even after students have benefitted, they still often feel as if they have not.

Rohrer (2012) suggests that the greatest benefit is in terms of discrimination. For example, a maths teacher who interleaves methods will find that students are more able to choose the correct method for completing a given problem. There is some of the effect here attributed to the effects of ‘spacing’ material but the effect exists still after taking this into account.

Our TouchPaper problem is about learning one set of information but teaching involves students remembering many pieces of information. Spacing is an important concept but our curriculum isn’t often designed in such a way as to make spacing manageable. Interleaving helps us to space content (thus the effects of spacing) plus we also get these additional benefits of interleaving. We could expect to see the benefits of interleaving at the ‘6 months’ interval of the TouchPaper question and further into the future.


Revisiting content isn’t just as straightforward as rereading or restudy. One important finding from our research was that testing is a way of improving learning, not just measuring it. So when we are talking about spacing intervals, one thing we should be doing at these intervals is testing!

This seems to fly in the face of common sense. Ask students and teachers and they would likely agree that studying is better than testing. Students certainly have the perception that testing isn’t as good as study. Simply rereading the material can create a sense of familiarity which increases the perception that this is better and that material is learnt. For teachers, we talk about how weighing the pig does not make it fatter. It is thought of as the ending point, not the means.

However, there are benefits associated with testing, most notably in retrieval. Roediger & Karpicke (2006) write: “Although restudying the passages exposed students to the entire set of information, testing permitted practice of the skill required on future tests and hence enhanced performance after a delay. If students retain information in their long term memory, they need to be able to access it, and testing may help to develop the cues and ‘retrieval routes’ to stored information.”

They conclude: “Frequent testing leads students to space their study efforts, permits them and their instructors to assess their knowledge on an ongoing basis, and—most important for present purposes—serves as a powerful mnemonic aid for future retention.”

The original TouchPaper question addresses reading, seeing and saying but perhaps we could add in ‘retrieving’ to that list?

Having laid out these ideas, and having barely scratched the surface of the original question, I will propose some points which now need addressing:

    • Teachers are not always curriculum designers and designing a course to cater for optimal learning gaps is difficult.
    • Much of the research base referred to above is on small-scale lists of facts and does this necessarily apply to larger bodies of knowledge and the schemata that underpin our subjects?
    • Does interleaving work better for some subjects than others?
    • What form should an interim test take to maximise retrieval?
    • How do we decide on the optimal spacing gap?
    • A classroom context is different to a research context. Can these research findings be transferred into classroom practice?

On the day, we concluded with the following simple recommendations:

Distribute study of content across multiple sessions rather than a massed session.

Make spacing manageable by weaving numerous topics together throughout the year rather than blocking topics discretely.

Quiz pupils regularly on previous content as the most effective way of retaining it.

A final point. The conversations, discussions and even disagreements during the course of the TouchPaper party helped shape ideas better than any CPD I’ve been involved with. Presentations from other groups contained many insights that have inspired a lot of thinking this week. It felt great to be a part of this occasion and I look forward to reading more blogs and seeing how things develop.

Some useful reading:

Using Spacing to Enhance Diverse Forms of Learning

Spacing Effects in Learning

Why Interleaving Enhances Inductive Learning

Interleaving Helps Students Distinguish Among Similar Concepts

Active Retrieval Promotes Meaningful Learning

Taking Memory Tests Improves Long Term Retention