Interleaving: can mixed practice boost your learning design?

Mixing it up

Learning design can be a complex process which should always begin by asking the question ‘Why?’, before moving on to the ‘What?’ and the ‘How?’ With so many variables in the mix, we already know that one learning design approach does not fit all.

Spacing, spirals and interleaving

So, where do we go next? A key skill in learning design is the ability to articulate the rationale for taking a particular approach. Terminology is everything! To communicate clearly, we need to understand the terminology we are using and how it impacts our design.

Massed practice

In massed practice, we cover separate topics as blocks. As the learner, if we don’t practice retrieving this knowledge over time, it is easy to forget what was covered in earlier topics.

Spaced practice

We use spacing to extend a learning experience over a period of time. Instead of designing an experience as a block of 1-day duration, we could chunk this down and spread it out over a 6-week period in sessions of 1-hour per week. This approach allows time for reflection in-between with each session designed to stimulate recall of the content covered in the previous session. This spacing and retrieval over an extended period improves recall of the topic, in comparison to massed practice.

Spiral learning

When we talk about spirals in learning design we are often referring to the concept of a ‘spiral curriculum’ (Bruner, 1960). In spiral learning, content for a topic is initially covered at a simple level. Opportunities are provided to apply this new knowledge with revision activities to consolidate learning. A spiral curriculum will revisit the same topic multiple times — each time increasing the depth of exploration and adding more detail — with application activities becoming more complex. The goal here is to work towards mastery of a topic by learning the basics and then building upon this by returning and going deeper each time.


We can think of interleaving as the opposite of massed practice. Instead of practising and completely mastering one topic before moving on to the next, with interleaving, we practice a topic for a shorter period of time before introducing other topics to the mix. For example, if we had 3 topics to cover, we could start by practising Topic 1, move on to Topic 3, then Topic 2 before returning to practice on Topic 1 again. The introduction of other topics is not a sequential process and can appear to be random.

Is interleaving the answer to improving knowledge retention?

Well, that depends on your perspective …

Summary: how mixed practice can boost your learning design

Let’s consider the design approach for online courses which are often self-directed without facilitation. As a learning designer, it is important to ensure that we introduce appropriate support and scaffolding to avoid frustrating and overwhelming the learner with ‘extraneous cognitive load’ which is caused by the difficulty involved in the task of learning itself (Sweller et al, 2011).

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