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How Students (Think They) Learn: The Plusses and Minuses of “Interleaving”
Andrew Watson
Andrew Watson

As the school year begins, teachers want to know: can mind/brain research give us strategies to foster learning?

We might also wonder: what will our students think of those strategies?

College Students Sitting in Hallway

It seems plausible — even likely — that students will prefer the strategies that help them learn. If those strategies help, why wouldn’t students like them?

Strategies to Foster Learning

Some classroom truths seem almost to basic to say out loud. For instance:

#1: We want our students to learn several different sub-topics within any particular topic.

And

#2: Students need to practice to learn.

When teachers think about those basic truths at the same time, we often adopt a specific strategy.

We ask students to practice (that’s #2) each individual subtopic (that’s#1) on its own. So:

Students practice identifying nouns, and then they practice identifying verbs, and then the practice identifying adjectives.

Or, angles, then circumferences, then areas.

Or, backhand, then forehand, then serve.

We could represent this strategy this way: AAA, BBB, CCC. Each sub-topic gets its own discrete practice session.

But, would a different strategy be better? How about: ABC, CBA, BCA?

In other words: should students jumble different topics together when they practice?

Interleaving: Old Research, and New

The answer to that question is YES: students SHOULD jumble different sub-topics together when they practice.

For research confirmation, you can check out this study by Rohrer and Pashler.

Or, for a broader synthesis, explore Agarwal and Bain’s great book, Powerful Teaching.

Or, you might ask a pointed question: “has this strategy been tested in actual classrooms, not just in psychology research labs?”

The answer to that question is also YES.

recently published study by Samani and Pan tried this strategy in a college physics class.

Sure enough, students learned more when their homework problems were interleaved than when sub-topics were practiced one at a time.

That is: students whose practice problems covered Coulomb’s Law by itself learned less than those whose practice problems also included capacitors and composite wires.

So, we arrive at this tentative teaching advice:

No doubt, you have your students practice — either in class, or with homework, or both.

When students practice, they should work on a few sub-topics at a time, not just one.

So far, so good.

Paradox: Teaching Solutions Create Studying Problems

Let’s return to the question that opened this blog post: do students prefer the study strategy that fosters learning. (They should; after all, it helped them learn!)

Reader, they do not.

Why?

In Samani and Pan’s study (and many others), students found that effective learning strategies are more difficult.

That is: they require more thought, and frequently lead to more short-term mistakes. (Students did relatively badly on the homework before they did relatively well on the tests.)

From one perspective, this finding makes perfect sense.

If we do difficult mental work, we will struggle and fail more often. And yet, all that extra hard thinking will ultimately lead to more learning. (Soderstrom and Bjork have written a GREAT review article on this topic.)

That encouraging perspective, however, runs into a perfectly understandable alternative: most people don’t like struggle and failure.

We shouldn’t blame students for disliking the interleaving. It hurt their heads. They did badly on the homework. YUCK.

As teachers, we have the long-term perspective. We know that short-term struggle leads ultimately to greater learning.

But, most students lack that perspective. They feel the struggle and the pain, but don’t recognize the long-term benefits.

Teaching Advice 2.0

Given all these findings, how should we structure students’ practice?

I think all these findings add up to this guidance:

First: interleave practice.

Second: tell students that you are doing so, and explain why.

The language you use and the level of explanation will, of course, vary by the age of the student. But, let them know.

Third: structure grading systems to value ultimate learning more than immediate understanding.

After all, if we both require interleaved practice (which is quite difficult) and grade students on the success of their practice, we will — in effect — force them to have lower grades. They will rightly feel the injustice of this instructional paradigm.

In other words: this practice strategy — in my view — does imply a grading policy as well.

TL;DR

Students, of course, must practice to learn.

Teachers should structure their practice to cover a few sub-topics simultaneously.

We should explain why we’re doing so; “interleaving” ultimately results in more learning.

We should create grading structures that account for the initial difficulty of interleaved practice.

If we get this balance right, students will willingly face early learning challenges, and ultimately learn more.


Rohrer, D., & Pashler, H. (2010). Recent research on human learning challenges conventional instructional strategies. Educational Researcher39(5), 406-412.

Agarwal, P. K., & Bain, P. M. (2019). Powerful teaching: Unleash the science of learning. John Wiley & Sons.

Samani, J., & Pan, S. C. (2021). Interleaved practice enhances memory and problem-solving ability in undergraduate physics. NPJ science of learning6(1), 1-11.

Soderstrom, N. C., & Bjork, R. A. (2015). Learning versus performance: An integrative review. Perspectives on Psychological Science10(2), 176-199.

Future Tense by Tracy Dennis-Tiwary
Erik Jahner, PhD
Erik Jahner, PhD

Being that approximately 20% of US adults have reported having an anxiety disorder in the last year, and many more have experienced situational anxiety which they are trying to reduce, Tracy Dennis-Tiwary suggests it is time for us to redefine our relationship with anxiety. The thrust of Future Tense: Why Anxiety Is Good for You (Even Though It Feels Bad) is that we need to shift our mindset concerning anxiety: anxiety is not a health crisis, but the way we cope with anxiety can be and the ways we cope with anxiety are missed opportunities for growth and productivity.

As someone who has been managing anxiety for many years, I found this book incredibly useful in that it helped reframe some of the beliefs I hold about anxiety even though I have read widely on the topic. The author approaches this reframing from a variety of perspectives from evolution and neuroscience to the social history of the terminology and diagnoses. She deconstructs our modern views on anxiety, helps us understand how these views have emerged, and helps us reconstruct our relationship with this emotional feeling. The experience of anxiety is framed by our cultural context and place in history, and we are capable of reframing the way we interact with the contexts and shifting our experience.

The research presented here also helps to clarify research and undo common misunderstandings. In particular, she brings awareness to the idea that anxiety is not a simple basic emotion, but a complex one that integrates multiple cortical areas and occurs through a complicated interaction of fear and reasoning. It is here, in this interaction, that we are able to exercise some executive control that can either make the anxiety functional or dysfunctional. She also points to the importance of human connection in scaffolding the way we channel this executive control.

The discussions on parenting and electronic media are particularly enlightening and display a real connection with the reader. There are so many broad generalizations in our social interactions about the impact of electronic media on our emotional state and misleading suggestions for parenting, but Tracy offers a critical look into these as well. She explains the weakness of some of our popular arguments through descriptions of her personal experiences as she came to understand her anxieties and the anxieties of those around her better.

The text is emotionally engaging while intellectually rigorous as Tracy does an excellent job of interweaving research with both her personal stories as well as our shared experience surviving the pandemic and the current political upheavals. We come to understand how she has experienced anxiety in her life the dynamics of the experience and through past, present, and future reflections. Similarly, the studies presented are done in a way that allows us to participate in thinking about how we have undergone or might react in similar situations. Keeping with the trend of the book she helps us notice our current behavior and mindset and then walks us through potential alternative exercises. The studies she presents encourage reflection making the science accessible.

This book was a quick weekend read that takes you on an intellectual and emotional journey. It will help you not only understand yourself better but also better understand the age we live in by looking at how our approaches to anxiety are woven into our cultural dynamics today.

How To Make Sure Homework Really Helps (a.k.a.: “Retrieval Practice Fails”)
Andrew Watson
Andrew Watson

Most research focuses narrowly on just a few questions. For instance:

“Does mindful meditation help 5th grade students reduce anxiety?”

“How many instructions overwhelm college students’ working memory?”

“Do quizzes improve attention when students learn from online videos?”

Very occasionally, however, just one study results in LOTS of teaching advice. For instance, this recent research looks at data from ELEVEN YEARS of classroom teaching.

Student Doing Homework with Laptop

Professor Arnold Glass (writing with Mengxue Kang) has been looking at the benefits of various teaching strategies since 2008.

For that reason, he can draw conclusions about those strategies. AND, he can draw conclusions about changes over time.

The result: LOTS of useful guidance.

Here’s the story…

The Research

Glass has been teaching college courses in Memory and Cognition for over a decade. Of course, he wants to practice what he preaches. For instance:

First, when Glass’s students learn about concepts, he begins by asking them to make plausible predictions about the topics they’re going to study.

Of course, his students haven’t studied the topic yet, so they’re unlikely to get the answers right. But simply thinking about these questions helps them remember the correct answers that they do learn.

In research world, we often call this strategy “pretesting” or “prequestions.”

Second, after students learn the topics, he asks them to answer questions about them from memory.

That is: he doesn’t want them to look up the correct answers, but to try and remember the correct answers.

In research world, we call this technique “retrieval practice” or “the testing effect.”

Third, Glass spreads these questions out over time. His students don’t answer retrieval practice questions once; they do so several times.

In research world, we call this technique “spacing.”

Because Glass connects all those pretesting and retrieval practice questions to exam questions, he can see which strategies benefit.

And, because he’s been tracking data for years, he can see how those benefits change over time.

The Results: Good & Bad

Obviously, Glass’s approach generates LOTS of results. So, let’s keep things simple.

First Headline: these strategies work.

Pretesting and retrieval practice and spacing all help students learn.

These results don’t surprise us, but we’re happy to have confirmation.

Second Headline: but sometimes these strategies don’t work.

In other words: most of the time, students get questions right on the final exam more often than they did for the pretesting and the retrieval practice.

But, occasionally, students do better on the pretest question (or the retrieval practice question) than on the final exam.

Technically speaking, that result is BIZARRE.

How can Glass explain this finding?

Tentative Explanations, Alarming Trends

Glass and Kang have a hypothesis to explain this “bizarre” finding. In fact, this study explores their hypothesis.

Glass’s students answer the “pretesting” questions for homework. What if, instead of speculating to answer those pretesting questions, the students look the answer up on the interwebs?

What if, instead of answering “retrieval practice” questions by trying to remember, the students look up the answers?

In these cases, the students would almost certainly get the answers right — so they would have high scores on these practice exercises.

But they wouldn’t learn the information well, so they would have low scores on the final exam.

So, pretesting and retrieval practice work if students actually do it.

But if the students look up answer instead of predicting, they don’t get the benefits of prequestions.

If they look up the answer instead of trying to remember, they don’t get the benefit of retrieval practice.

And, here’s the “alarming trend”: the percentage of students who look up the answers has been rising dramatically.

How dramatically? In 2008, it was about 15%. In 2018, it was about 50%.

Promises Fulfilled

The title of the blog post promises to make homework helpful (and to point out when retrieval practice fails).

So, here goes.

Retrieval practice fails when students don’t try to retrieve.

Homework that includes retrieval practice won’t help if students look up the answers.

So, to make homework help (and to get the benefits of retrieval practice), we should do everything we reasonably can to prevent this shortcut.

Three strategies come quickly to mind.

First: don’t just use prequestions and retrieval practice. Instead, explain the logic and the research behind them. Students should know: they won’t get the benefits if they don’t do the thinking.

Second: as must as is reasonably possible, make homework low-stakes or no-stakes. Students have less incentive to cheat if doing so doesn’t get them any points. (And, they know that it harms their learning.)

Third: use class time for both strategies.

In other words: we teachers ultimately can’t force students to “make educated predictions” or “try to remember” when they’re at home. But we can monitor them in class to ensure they’re doing so.

These strategies, to be blunt, might not work well as homework — especially not at the beginning of the year. We should plan accordingly.

TL;DR

Prequestions and retrieval practice do help students learn, but only if students actually do the thinking these strategies require.

We teachers should be realistic about our students’ homework habits and incentives, and design assignments that nudge them in the right directions.

 

Glass, A. L., & Kang, M. (2022). Fewer students are benefiting from doing their homework: an eleven-year study. Educational Psychology42(2), 185-199.

The Best Book on Cognitive Load Theory: Ollie Lovell to the Rescue
Andrew Watson
Andrew Watson

Teaching ought to be easy.

After all, we have a functionally infinite amount of long-term memory. You don’t have to forget one thing to learn another thing — really.

So: I should be able to shovel information and skills into your infinite long-term memory. Voila! You’d know everything

Alas, to get to your long-term memory, “information and skills” have to pass through your working memory. This very narrow bottleneck makes learning terribly difficult — as teachers and students well know.

If only someone would come up with a theory to explain this bottleneck. If only that theory would help teachers and students succeed despite its narrow confines.

Good News, with a Twist

Happily, that theory exists. It’s called “cognitive load theory,” and several scholars in Australia (led by John Sweller) have been developing it for a few decades now.

It explains the relationship between infinite long-term memory and limited working memory. It explores practical classroom strategies to solve the problems created by this relationship.

Heck, it even muses upon evolutionary explanations for some quirky exceptions to its rules.

In other words, it has almost everything a teacher could want.

Alas — [warning: controversial opinion] — it does include one glaring difficulty.

Cognitive load theory helps educational psychologists talk with other educational psychologists about these topics.

However, it relies on on a long list of terms, each of which describes complex — sometimes counter-intuitive — concepts.

If you start reading articles based on cognitive load theory, you might well discover that …

… a particular teaching practice works this way because of the “split attention effect” (which doesn’t mean exactly what it sounds like),

… but it works that way because of the “expertise reversal effect,”

… and “element interactivity” might explain these contradictory results.

For this reason, paradoxically, teachers who try to understand and apply cognitive load theory often experience cognitive overload.

As a result, teachers would really benefit from a book that explains cognitive load theory so clearly as not to overwhelm our working memory.

Could such a book exist?

Ollie Lovell To The Rescue

Yes, reader, it exists. Oliver Lovell has written Sweller’s Cognitive Load Theory In Action (as part of Tom Sherrington’s “In Action” series).

Lovell’s book does exactly what teachers want it to do: explain cognitive load theory without overloading our cognitive faculties.

Lovell accomplishes this feat with three strategies.

First, he has an impressive ability to explain cognitive load theory concepts with bracing clarity.

For instance, let’s go back to that “expertise reversal effect.” Why might a teaching strategy benefit a novice but not an expert?

Lovell’s answer: redundancy. Redundant information taxes working memory. And, crucially:

“What is redundant for an expert is not redundant for the novice, and instructional recommendations are reversed accordingly.”

That’s the “expertise reversal effect.” Pithy, clear, sensible.

Because he writes and explains so clearly, Lovell helps teachers understand all that cognitive load theory terminology without feeling overwhelmed.

Second, Lovell gives examples.

SO MANY CLASSROOM EXAMPLES.

Whatever grade you teach, whatever topic you teach, you’ll find your discipline, your grade, and your interests represented. (I believe Lovell is a math teacher; as a high-school English teacher, I never felt slighted or ignored.)

Geography, piano, computer programming. It’s all there.

Knowing that clear explanations of worked examples can reduce working memory load, he provides plenty.

Practicing What He Preaches

Third, Lovell simplifies needless complexities.

Students of cognitive load theory will notice that he more-or-less skips over “germane” cognitive load: a category that has (ironically) created all sorts of “extraneous” working memory load for people trying to understand the theory.

He describes the difference between biologically primary and biologically secondary learning. And he explains the potential benefits this theory offers school folk.

However, Lovell doesn’t get bogged down in this niche-y (but fascinating) topic. He gives it just enough room, but not more.

Heck, he even keeps footnotes to a minimum, so as not to split the reader’s attention. Now that’s dedication to reducing working memory load!

Simply put: Lovell both explains and enacts strategies to manage working memory load just right.

In Brief

No doubt your pile of “must read” books is intimidatingly large.

If you want to know how to manage working memory load (and why doing so matters), Lovell’s Cognitive Load Theory in Action should be on top of that pile.


A final note:

I suspect Lovell’s explanations are so clear because he has lots of experience explaining.

Check out his wise, thoughtful, well-informed podcasts here.