Interleaving practice makes perfect: “mix it up” to learn faster

Two students are learning to play three songs on the piano: "Twinkle, Twinkle, Little Star," "Mary Had a Little Lamb," and "Chopsticks."

Student A decides to learn each song on its own, perfectly, before moving on to the next.

Student B decides to mix it up by practicing all three songs every day.

Who do you think will be the first to perfect all three songs?

According to cognitive scientists, the answer is almost definitely Student B (assuming Student A isn’t Elton John).

Why? Because Student B made use of a powerful learning strategy called interleaving or mixed practice, which has been widely shown to improve learning and retention.

The problem is, while interleaving study practice is a powerful learning tactic, it’s also woefully underused in the formal academic environment. Even most adaptive learning tools and apps simply stop at spaced repetition, without realizing how powerful spaced repetition can be with the added benefit of interleaving practice!

That’s why the team here at Brainscape did two things:

1. We wrote this guide: to help you understand how YOU can harness interleaving practice to inject a little high-octane fuel into your own learning journey; and
2. We became the first-ever study app to integrate both spaced repetition and interleaving practice into our learning algorithm!

Hi! We’re Brainscape

We’re the brains, minds, and hearts behind the world’s smartest study and flashcard app, which, since its conception, has leveraged spaced repetition, active recall, and metacognition to empower learners to learn anything TWICE as efficiently as traditional study methods.

Now, in one of the most important feature releases in our history, Brainscape has launched ‘Smart Study’, a single button that allows you to (1) instantly and effortlessly start studying (with all the sexy benefits the app has historically offered) but (2) with interleaving learning strategy now applied to our spaced repetition study algorithm. (Also, it’s completely free for all users.)

We’ll talk more about ‘Smart Study’ later but right now, let’s take a closer look at what interleaving practice actually is, why it helps you to learn more efficiently, and then, how Brainscape harnesses this powerful learning strategy.

What is an interleaving study strategy?

“Interleaving practice” is a bit of a mouthful, and yet it’s the basic principle by which nearly ALL of life’s lessons and skills outside the classroom are learned: randomly, haphazardly, and unpredictably.

Think about it. In the real world, knowledge is seldom presented to us in the same ordered, discrete, and “blocked” ways it’s presented to us in the classroom and in academic textbooks. And by “blocked” I mean a one-hour biology lecture, a textbook chapter on World War 2, or a math problem set on derivatives.

Instead, fragments of information bombard us constantly, like meteor shards pounding into the Earth’s atmosphere. And with the advent of modern technologies like the internet and social media, the bombardment is more relentless than ever.

One second you could be watching an IG reel on how to make garlic focaccia, or reading a Medium.com article on the tell-tale signs your friend is a narcissist; and the next, it could be a blog on keeping New Year’s resolutions, a new TikTok dance tutorial, or the latest news headlines.

Every day, you’re likely repeatedly exposed to similar information through blogs, articles, and news headlines (based on your search history) and although that information gets delivered to you in a randomized and unpredictable stream, the themes you encounter tend to stick in your brain WAY more effectively than, for example, the stuff you read about in your economics textbook. And this SUCKS because it’s the latter that you need to remember so that you can pass your exams and graduate!

But this is where an interleaving study strategy comes in.

Interleaving practice is a learning strategy that involves intentionally alternating between different types of tasks or concepts rather than focusing on one specific task or concept at a time.

In the context of learning, this could mean many things:

• Studying concepts taken at random from an entire textbook chapter, rather than in an ordered, chronological fashion;
• Studying concepts taken at random from a number of different subjects, rather than focusing exclusively on a single subject;
• Regularly switching between different study modalities, such as watching video lectures, making study notes, practicing problem sets, studying flashcards, etc.; and
• Regularly switching between study and non-study-related tasks, which is similar to the afore-mentioned, except that it intersperses things like going for a quick walk or doing a load of laundry between study sessions.

(Importantly, this does NOT include dopamine-spiking activities like watching TV or playing video games, which will only derail your focus.)

Now, you may be thinking: “How the heck can you learn a subject properly if you’re constantly bouncing back-and-forth randomly between topics like this?” But that's the thing: it's not random.

You’re intentionally interweaving concepts across a subject or several subjects, which forces your brain to re-contextualize every concept it comes across, which builds much stronger connections to that information.

Sure, the first time you’re taught something, like a historical event or a biological process, it’s likely best presented in logical / chronological order from beginning to end. But once you have that 30,000 foot view of the concept, it’s interleaving study practice, paired with spaced repetition*, that’s going to help you bank the facts in your brain’s permanent memory vault so much faster than traditional study methods.

* Spaced repetition is the repeated exposure to information or practicing of a skill at time intervals that are spaced according to how well you understand a concept: more often if you don’t know it well and less often if you don’t. (Read more about it here.)

Why is interleaving practice such an effective learning strategy?

One of the main reasons interleaving practice improves learning and retention is because it forces the brain to constantly switch between different types of information, which requires effort. And when it comes to how your brain is designed to work, mental effort = strong neural connections just like physical work = powerful muscles.

Think of your brain as a vast library for every piece of information you have ever come across.

Whenever you learn something new, your brain files that information in its library. If you access that information often, your brain is going to come to learn exactly where it’s stored and access it pretty fast when you need it again. (This is the benefit of spaced repetition.)

But if you force your brain to repeatedly, randomly recall that information by jumping between subjects or concepts, it’s going to learn SEVERAL pathways to that information. And the more neural pathways your brain establishes to a piece of information, the better you’ll remember it until, eventually, it requires no work at all for your brain to recall that information from scratch.

This process, known as "cognitive conflict," helps to strengthen connections between neurons and improve memory. Now, contrast this with traditional “blocked” learning where your brain is deeply entrenched in a single subject or concept and so it only establishes a single and narrow pathway to that information.

Do you see now why an interleaving learning strategy is more effective?

By the way: the opposite of interleaving practice is blocked practice in which you practice one type of problem or skill at a time, which—for reasons that blow our minds—is pretty much the default approach taken by the modern education system.

Interleaving practice helps students establish meaningful connections between different concepts

Interleaving study practice also allows students to make more meaningful connections between different concepts, which prevents themes from becoming too reliant on a specific pattern, strategy, or approach to solve a problem. In other words, it deepens our understanding of individual concepts and how they differ from similar concepts.

Think about skills like playing a musical instrument:

You might learn a song really well (chords C, G, Am, F) but if I now suddenly asked you to play those very same chords, just in a different order (C, F, G, F), you may suddenly find yourself struggling. This means that even though you know how to play all those chords in sequence, you still kinda have to learn the new song from scratch.

The punchline here is that you’re going to achieve fundamental mastery of that instrument much earlier if you learn to play the different chords completely at random, as opposed to always in the same order… because if your brain becomes too attached to a particular pattern, it’ll struggle to differentiate between the individual concepts or, in this case, chords. And THIS will hinder your ability to learn new songs quickly.

Being overly attached to specific patterns, strategies, or approaches is the same reason a lot of people struggle to recite the alphabet backwards. We all know the alphabet like the back of our hands, but our memory of it is so deeply grounded in the song we’re taught as infants that things totally fall apart when required to recite it in the opposite order.

Interleaving practice prevents ALL OF this: it prevents our brains from attaching individual concepts (like chords or letters) to others, thereby strengthening our understanding of each one, enabling us to learn it and remember it as a discrete unit that fits into a greater logical tapestry.

Unfortunately, however, as we touched on in the beginning of this guide, traditional academia doesn’t really leverage interleaving practice to teach information, probably because it’s just easier to take a systematic, chronological “blocked” approach to dispensing lessons.

(Plus there are obvious practical difficulties of, for example, your math teacher throwing down a bunch of random history or biology facts in the middle of a lesson.)

So, how can interleaving practice be realistically applied to your own learning journey?

How to make interleaving practice work for you

Actually, it wouldn’t be all that practically difficult for a math teacher to introduce an interleaving learning strategy in their classroom. One way would be to simply give students mixed problem sets that include a variety of math problems, or at least a few previously-taught concepts thrown in.

In other words, instead of JUST doing a math assignment on what you’re currently learning about in class, your problem set would include the odd algebra question, perhaps one on geometry, and surds and logarithms. This not only refreshes the older information but, through interleaving practice, strengthens your brain’s neural connections to the procedures it must follow to solve those math problems.

(You could do this yourself by writing a whole bunch of math problems or equations, each on a separate square of paper, which you then throw into a pile and draw at random to practice your math skills. Fold the paper so that the answer on the back is hidden. Or, even better, use Brainscape to make digital flashcards and save a tree!)

Here’s another example:

Let’s say you're studying for a history exam. You've been given a list of topics that will be covered on the exam, including ancient civilizations, world wars, and the American Revolution.

Instead of studying each topic individually, you could use interleaving practice to mix things up and keep things interesting. So you break each chapter down into short sections and spend 15 to 20 minutes studying ancient civilizations, then 15 to 20 minutes studying world wars, and finally 15 to 20 minutes on the American Revolution. The next day, however, you mix it up by starting with the American Revolution, then the world wars, and finally ancient civilizations.

Alternatively, you could take all of your flashcards from these three history chapters, mix them together, and then study them at random so that you simply don’t know which topic is going to come up next.

This random, interleaving study strategy will help you to learn more efficiently because it forces you to constantly switch between different concepts, which helps to deeply reinforce the material in your memory.

(Plus, it keeps things interesting!)

The most powerful way to use interleaving practice, however, is to use it to bounce back-and-forth between totally different subjects (e.g. including a handful of Spanish vocab/conjugation flashcards with your biology flashcards). The more extreme the “brain acrobatics” the more powerful those neural connections become!

So, in summary, here are the ways that you can harness interleaving practice in your learning journey:

• Study flashcards that test you on an entire textbook chapter at random, rather than in a chronological fashion;
• Studying flashcards that test you on a number of different subjects at random, rather than focusing exclusively on a single subject.
• Regularly switching between different study modalities, for example, a language teacher might have students alternate between reading, writing, and speaking activities.
• Regularly switching between study and non-study-related tasks, like going for a quick walk or doing a load of laundry between study sessions.

Now, the reason we’re using flashcards as an example of how to integrate interleaving practice in your study strategy is because (1) flashcards are the perfect tool for distilling knowledge down into its constituent facts and concepts; (2) they make it easy to repeat those individual concepts at customizable time intervals; and (3) they can be organized in a variety of ways, depending on your unique needs.

All of these factors make flashcards—and especially digital flashcards—the perfect vehicle for interleaving practice… and Brainscape is the first flashcard app to combine this science-backed strategy with spaced repetition.

Now, let’s finally explain how Brainscape can take any subject/s you’re learning and help you leverage interleaving practice to learn them faster and remember them for longer…

Interleaving study practice with Brainscape’s ‘Smart Study’ feature

Brainscape’s ‘Smart Study’ feature is really just a single button on your app’s dashboard. By tapping that button, Brainscape will painlessly feed you a personalized study stream that relentlessly attacks your weaknesses across all the subjects on your dashboard, whether you made those flashcards yourself or sourced them from Brainscape’s library of expert-curated and user-generated content.

‘Smart Study’ is also easily customizable so that you control exactly what mix of subjects you study. Simply tap on the “configure” icon next to the ‘Smart Study’ button, adjust the percentage of flashcards you’d like to see from each class, and the algorithm will do the rest.

So, let’s say you’ve got a huge geography exam coming up: you can set your percentages to be equal across all of your geography decks and classes—but ZERO on any non-geography topic—so that you’re receiving the perfect interleaved mix of geography-specific flashcards.

To benefit from interleaving practice, remember that the more your brain is compelled to jump between subjects, the stickier those concepts will become. So if you really want to learn for that geography exam efficiently, you could set your geography flashcards to 70% with, perhaps, some flashcards from Brainscape’s Knowledge Rehab and Vocab Workout collections thrown in. (Or whatever other subject you’d like to focus on.)

Alternatively, you could set your percentages for ALL your subjects to be the same, allowing you to use Brainscape as a powerful review tool for multiple subjects at once.

You can also configure ‘Smart Study’ once and forget about it or regularly fine-tune it to align seamlessly with your study goals for that day, week, or month. You have complete control. Either way, you’ll be giving your learning a fierce boost with Brainscape’s science-backed study strategies.

A final word on Interleaving practice

In real life, we organically learn new information and master new skills in an interleaved fashion. It’s fundamentally how our brains are wired to receive (and retain) information. And so, interleaving study practice is a proven strategy to help students learn more efficiently.

By mixing up your practice, subjects, and topics and incorporating various activities, you can become a more confident and successful learner. One way to achieve this with little more than the tap of a button is Brainscape’s ‘Smart Study’ feature, which is built into the app and is 100% free for all learners.

So now that you have a more sophisticated understanding of interleaving practice and the tools to incorporate it into your learning journey, go forth, practice, and make perfect!

References

Brunmair, M., & Richter, T. (2019). Similarity matters: A meta-analysis of interleaved learning and its moderators. Psychological Bulletin, 145(11), 1029–1052. https://doi.org/10.1037/bul0000209

Chen, W., Chen, C., Li, B., & Zhang, J. (2022). Applying interleaving strategy of learning materials and perceptual modality to address secondary students’ need to restore cognitive capacity. International Journal of Environmental  Research and Public Health/International Journal of Environmental Research and Public Health, 19(12), 7505. https://doi.org/10.3390/ijerph19127505

Firth, J., Rivers, I., & Boyle, J. (2019). A Systematic Review of Interleaving as a Concept Learning Strategy. Social Science Protocols, 2, 1–7. https://doi.org/10.7565/ssp.2019.2650

Nguyen, H. P. (2021, June 11). How to use interleaving to foster deeper learning. Edutopia. https://www.edutopia.org/article/how-use-interleaving-foster-deeper-learning/

Rohrer, D. (2012). Interleaving Helps Students Distinguish among Similar Concepts. Educational Psychology Review, 24(3), 355–367. https://doi.org/10.1007/s10648-012-9201-3

University of Arizona. (2024). L2L Strategy - Interleaving. Academic Affairs. https://academicaffairs.arizona.edu/l2l-strategy-interleaving

Wadsworth, W. (2022, November 11). Interleaved practice 101: what really is interleaving and how to REALLY use it in teaching and learning. Exam Study Expert. https://examstudyexpert.com/interleaving/

Waxer, M., & Morton, J. B. (2012). Cognitive conflict and learning. In Springer eBooks (pp. 585–587). https://doi.org/10.1007/978-1-4419-1428-6_280