The struggle of switching between different topics during practice creates “desirable difficulty” that strengthens memory and improves your ability to apply knowledge flexibly in new situations.
What Is Interleaving?
Imagine practicing for a reading comprehension test. The intuitive approach is to group your practice by type: do all the inference questions first, then all the main idea questions, then all the vocabulary questions. This is called blocked practice — focusing on one skill or topic at a time before moving to the next.
Interleaving is the opposite. Instead of practicing all of one type before moving on, you mix different topics, skills, or problem types together in your practice session. Inference question, then main idea, then vocabulary, then inference again. The sequence feels jumbled, even chaotic.
And here’s the paradox: interleaved practice feels harder and produces worse performance during practice sessions, but leads to significantly better retention and transfer when tested later. The confusion you feel while mixing topics isn’t a sign that learning is failing — it’s a sign that learning is working.
The Science Behind Interleaving
When you practice in blocks, your brain quickly figures out the pattern. All inference questions? Use the inference strategy. All vocabulary? Use context clues. You don’t have to think about which approach to use — you already know because you’re in the “inference block.” Performance feels smooth, and you feel like you’re mastering the material.
But this fluency is deceptive. In real reading situations, problems don’t come labeled. You encounter an inference question, then a tone question, then a structure question — and you have to figure out which approach to use for each. Blocked practice never trains this discrimination skill.
Interleaving forces your brain to constantly discriminate between different problem types and select the appropriate strategy. This process — figuring out what kind of problem you’re facing — is exactly what you need for real-world application. Blocked practice lets you skip this crucial step.
Research demonstrates the effect consistently. In one famous study, students learning to identify painting styles performed better during blocked practice but dramatically worse on the final test. Students who interleaved — seeing paintings from different artists mixed together — performed worse during practice but 60% better on the delayed test.
The pattern appears across domains: math problems, sports skills, music practice, medical diagnosis, and yes, reading comprehension. Mixed practice creates durable, flexible knowledge that transfers to new situations.
Why This Matters for Reading
Reading comprehension tests don’t organize questions by type. Neither does real-world reading. One paragraph requires you to infer the author’s stance; the next tests whether you understood a technical term; the third asks about organizational structure. Your brain must recognize what each question demands and retrieve the appropriate strategy.
If you’ve only practiced in blocks, you’ve never actually practiced this recognition task. You’ve practiced applying strategies, but not selecting them. When questions come mixed — as they always do in real tests — you’re doing something you’ve never trained for.
Interleaving also improves your understanding of what makes each question type distinct. When you switch from inference to vocabulary to main idea, the contrast highlights the unique features of each. Blocked practice obscures these differences because you never see them side by side.
Blocked approach: Read 5 passages, answer all inference questions. Then read 5 more passages, answer all main idea questions. Then vocabulary questions.
Interleaved approach: Read passage 1, answer one inference question, one main idea question. Read passage 2 (different genre), answer vocabulary question, tone question. Continue mixing both passage types and question types.
Result: The interleaved approach feels harder and produces lower scores during practice. But on the actual test a week later, interleaved practice produces significantly better performance.
How to Apply Interleaving
Mix Passage Types
Don’t read five science passages in a row, then five humanities passages. Mix them. Read a biology article, then an economics analysis, then a literary critique. The switching forces you to adjust your reading approach for different content types — a skill you’ll need in real reading situations.
Mix Question Types
When practicing comprehension questions, resist the urge to group by type. Don’t do all inference questions at once. Mix inference, vocabulary, structure, tone, and main idea questions within each practice session. The constant switching trains the recognition skill that blocked practice neglects.
Mix Study Sessions
If you’re studying multiple subjects or topics, interleave them within a single study session rather than dedicating entire sessions to one topic. Twenty minutes of reading practice, then twenty minutes of math, then back to reading. This larger-scale interleaving produces benefits beyond topic-specific practice.
Blocked practice feels more productive because performance during practice is higher. Don’t be fooled. The feeling of fluency during blocked practice is a poor predictor of long-term retention. When practice feels too smooth, you’re probably not learning as effectively as you could be.
Common Misconceptions
“I Should Master One Topic Before Moving On”
This intuition is wrong for most learning situations. Once you have basic competence — you understand the concept, you can execute the skill — switching to interleaved practice produces better long-term results than continuing blocked practice. Mastery comes from interleaved practice, not from blocked repetition.
“Struggling Means I’m Not Learning”
The struggle of interleaved practice is where learning happens. If practice feels easy and smooth, your brain isn’t working hard enough to build durable memories. Embrace the difficulty — it’s the signature of effective learning.
“Interleaving Is Always Better”
There’s one important exception: initial learning. When first encountering a brand new concept or skill, some blocked practice helps establish basic understanding. Use blocking to build initial competence, then switch to interleaved learning to solidify and strengthen that knowledge.
Putting It Into Practice
Start small. In your next practice session, deliberately mix two or three different question types or passage genres. Notice that it feels harder — and remind yourself that this difficulty is productive.
Track your results. You’ll likely see lower scores during practice but better retention when you test yourself days later. This pattern — worse practice performance, better test performance — is the hallmark of effective interleaving.
Combine interleaving with other evidence-based strategies. Interleave different topics within a spaced repetition system. Use retrieval practice rather than rereading, and interleave the topics you’re retrieving. These techniques compound each other’s benefits.
For more on building effective practice routines that actually stick, explore the complete Strategies & Retention collection in our Reading Concepts hub.
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