Best Practice

Impactful interleaving strategies that can be used in the classroom

Retrieval practice & metacognition Pedagogy Lesson planning In the classroom
Interleaving techniques have been shown to improve the retention of knowledge but can be difficult to implement given curriculum constraints. Andrew Jones offers some simpler ways of interleaving topics in your teaching
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Interleaving, or interleaved practice, emphases the “mixing up” of topics being studied or recalled in order to facilitate improved retention and retrieval of knowledge and skills.

Importantly, interleaving is linked to spacing, or distributed practice, as the mixing up of topic areas will allow for them to be revisited at spaced intervals.

For instance, some advocates of interleaving argue we should avoid teaching schemes of learning or units of work in sequentially ordered blocks, such as A1, A2, A3, B1, B2, B3, C1, C2, C3, and instead teach topics in cyclical, or spaced, segments, such as A1, B1, C1, A2, B2, C2, A3, B3, C3 (for further elaboration, see Rohrer, 2012).

However, after briefly exploring how interleaving works, this article will point out that completely overhauling our current curriculum and syllabuses is easier said than done. It will then suggest some simpler ways we can use interleaving in our classrooms.

 

How interleaving works

Experimental psychologist Stephen Pan (2015) states that interleaving enhances the brain's ability to discriminate between concepts, thereby preventing confusion during knowledge recall. Moreover, research indicates that requiring learners to decipher and categorise recalled information improves overall knowledge retrieval by increasing cognitive effort, a phenomenon referred to as "desirable difficulty" by Elizabeth Bjork and Robert Bjork (2011).

Pan also suggests that interleaving strengthens memory associations between concepts, leading to a deeper understanding of the taught material, especially concerning causes, effects, processes, or broader contextual information. Consequently, interleaved practice proves particularly valuable for subjects with synoptic exam papers where students must apply diverse strands of knowledge to specific questions or problems.

A number of SecEd articles have explored the benefits of interleaving and are worth consulting if you are wanting to better understand its overall importance (Still, 2021; Still, 2022; Dabell, 2020; Webb, 2022).

 

Evidence of interleaving’s impact

Various studies have reported the benefits of interleaving on learning, such as improving learners’ ability to identify paintings by specific artists (Kornell & Bjork, 2008; Kang & Pashler, 2011), classifying different bird species (Wahlheim et al, 2011), problem-solving in engineering (Butler et al, 2014) and its use in medicine (Kao, 2016).

Moreover, some school-based studies have demonstrated the impact of interleaving on the acquisition of mathematical skills, including fractions, addition, multiplication problems, and geometry (Dodson, 2020). Additionally, a recent study conducted in the US, comparing blocked and interleaved practice of maths problems across five schools in Florida, revealed that the interleaved group significantly outperformed the blocked group (Rohrer et al, 2020).

Therefore, interleaving is an idea we should consider seriously if we want to improve pupils' overall progress and attainment.

 

But is interleaving practical?

In a previous SecEd article on “desirable difficulties” (Jones, 2022), I suggested that a wholesale reworking of the curriculum or subject-specific syllabuses may cause some alarm among teachers, especially as many have always taught their subjects in blocks.

It is important, nonetheless, to recognise that this is not a case of stubborn teachers refusing to change in the face of new, innovative, and exciting evidence. There are a number of sound reasons for resisting change, such as laying the foundations of knowledge through core topic areas before building on these in later units of study with more bespoke skills, facts, or theories.

In my own subjects, for example, pupils need to understand the nature of God before studying miracles in religious education, or the key ideas of feminism before applying it to educational attainment in sociology.

Furthermore, many GCSE and A level syllabuses are structured around block learning, as are many aspects of the national curriculum. Forcing interleaving upon teachers who are guiding pupils through these syllabuses might be more harmful if it is carried out in a knee-jerk and haphazard way.

Subsequently, although many colleagues have found ways to interleave syllabuses in full (see, for instance: Fawcett, 2014; Didau, 2015; Cox, 2016), for most of us a revolution in how we plan and deliver the curriculum is clearly problematic.

 

Practical interleaving

However, there are ways around the issues outlined above, which can still allow us to teach in blocks. These include interleaving practice through the following approaches.

 

Starter activities: These are a great way to interleave questions from previously taught units. In my lessons, as well as in the lessons of many of my colleagues, starters consist of six questions: three from the previous lesson and three from a previous unit. The latter questions are planned in cycles to ensure a balanced coverage of previously taught content.

Ad-hoc questioning: Although the above starters are planned, I regularly ask ad-hoc questions during lessons based on previous units when opportunities arise. For example, if the class is discussing forgiveness and reconciliation in a unit on crime and punishment in RE, I will ask if pupils can remember what Jesus proclaimed about forgiveness when he was on the cross, which was studied in a previous unit on Christian beliefs. In sociology, I would do the same when students are learning about labelling in a unit on crime and deviance, which was previously studied in relation to education. This is, essentially, quick, and very basic recapping.

Low-stakes tests: These are often used as plenaries in my lessons, and if 10 questions are used, five will be based on the current lesson and five will be based on previous content. I tend to assign these questions randomly as the low-stakes tests are used intermittently (about once every three or four lessons), unlike the more structured use of starters, homework, and assessments.

Homework: Each week, I assign three substantial homework questions, including one on the current topic taught and two others on previous topics, which are again planned to ensure there is equitable coverage of past content.

Assessments: Every half-term, my RE pupils sit assessments, which include a section on the current topic and a section on a previous unit. As mentioned earlier, these assessments are scheduled to ensure that previous units are assessed equally.

Consolidation/revision lessons: These lessons can take place half-way through units of work or at the end of topics as they allow pupils to briefly revisit previously taught content. Although their initial introduction might be confusing, after time their purpose should become clear to pupils and allow them the opportunity to review their learning to date. The “station rotation model” can be used here as it engages pupils by facilitating quick rotations through related concepts in small groups (Nguyen, 2021).

 

Other considerations

Other important things to consider when interleaving include:

  • Refrain from interleaving excessively dissimilar topics: If the two topics you intend to interleave are significantly divergent, the mixed practice could impede pupils’ learning rather than enhance it. Therefore, you should only interleave topics within the subject domain you teach.
  • Avoid interleaving overly similar topics: If the two topics you wish to interleave are too alike, it may resemble blocked practice, which diminishes the benefits of interleaving.
  • Introduce variety in a logical manner: Ensure that the criteria you employ for mixing the material enables you to maximise the advantages of interleaving. A key facet here is only interleaving previously taught content. Do not use new content as misconceptions and confusion may result.

 

Conclusion

Interleaving holds potential for enhancing pupil progress and achievement but implementing it wholesale might not be practical in all contexts. Therefore, and although easier in some subjects than others, implementing interleaving through strategies like starters, ad-hoc questioning, and assessments can surely be practical beyond my subject specialisms.

Andrew Jones is assistant headteacher at The Reach Free School in Hertfordshire. Follow him on X (Twitter) @abowdenj and find his previous articles for SecEd via www.sec-ed.co.uk/authors/andrew-jones

 

Further information & resources