If you have even a passing interest in cognitive science-based approaches to teaching and learning, then you will be well aware of the benefits of “retrieval practice”.

Retrieval practice involves teachers providing frequent opportunities for children to remember what they’ve learned, often through low-stakes testing, until information becomes deeply embedded and eventually takes less effort to recall.

As a recent overview by American researchers Daniel Corral and Shana Carpenter confirms, this approach provides “long-lasting” benefits in the form of “significant and often sizeable advantages on later memory”.

It is also well known that it’s helpful to space retrieval practice out over several shorter sessions, rather than conducting retrieval in one long, intense session, as a 2021 review by Alice Latimier and colleagues highlights.

But could the benefits of retrieval and spaced practice be developed further? An important, but somewhat overlooked 2024 study by Polish researcher Ewa Butowska-Buczyńska and colleagues suggests that introducing greater variability into learning - through “variable retrieval practice” - can enhance students’ ability to retain knowledge.

What is variable retrieval practice?

According to Butowska-Buczyńska and colleagues, variable retrieval practice occurs “when the same information is processed in a slightly different way at each retrieval attempt, rather than always in the same way”.

During the experiment, participants were asked to learn Finnish words, such as the word lattia, which means floor. As part of the process, they were either given constant or variable retrieval cues. For example:

And the results? The researchers found that adding variability “clearly produces robust benefits for memory performance”. This, they noted, suggests that variable retrieval practice is a “learning technique of fundamental importance”.

But what might variable retrieval look like in the classroom? Sometimes it might be as simple as varying the phrasing of the questions used to prompt students’ recall of a particular piece of information. Here’s an example from computer science:

Many teachers will already vary the questions they use, but being intentional and explicit in planning for variable retrieval practice means that students are more likely to experience the benefits.

You might assume that variability only works when testing straightforward factual recall. However, Butowska-Buczyńska and colleagues’ research highlights how variable retrieval also boosted the effectiveness of learning when students were given questions requiring deeper thinking, such as variations on: “How do rift and subduction zones help to recycle the Earth’s crust?”

To develop higher-order thinking, an English teacher, for example, might introduce variability when asking retrieval questions, such as:

As for other subjects, 2015 research from the University of Memphis investigated whether variable retrieval practice is useful for material requiring “deeper, integrated learning or transfer”. In this case, complex statistical concepts.

The study found that there was a “slower forgetting rate” when variable retrieval was used during practice, suggesting that even with this type of material, learning is “more durable” when practice is variable.

Should teachers switch to variable retrieval immediately?

Given the evidence suggesting that variability increases memory performance, you might be tempted to immediately revamp your retrieval quizzes. Before doing so, however, you should be aware of a very important caveat highlighted in the study by Butowska-Buczyńska and colleagues.

The researchers found that the benefits of variable retrieval were “severely underappreciated” by learners, who “judged learning to be more effective with constant rather than variable cues”.

In other words, students didn’t enjoy the additional challenge involved with variable retrieval and mistakenly believed they retained knowledge better when they were asked the same question repeatedly.

This illustrates how students often misjudge the effectiveness of learning strategies and fail to appreciate the ”desirable difficulties” that are inherent in the most impactful study techniques. As Elizabeth and Robert Bjork point out in their seminal 2011 paper, “conditions that create challenges and slow the rate of apparent learning often optimise long-term retention and transfer”.

Giving verbatim responses to the same retrieval question over and over might well be more appealing to students than having to show a deeper grasp of meaning by answering differently worded variations. Yet the more difficult variable version is likely to be more helpful in the long run.

For this reason, when introducing variability to retrieval quizzes, it’s vital that you teach students about why you are doing this. That’s the first step in ensuring that they use the most effective strategies, even if they are going to dislike using them.

Mark Roberts is an English teacher and director of research at Carrickfergus Grammar School. His new book, Fail better: how teachers can help students overcome failure, perfectionism, procrastination, impostor syndrome and test anxiety, will be published in March 2026

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