Most students study by topic. They work through all the algebra problems, then all the geometry problems, then all the statistics problems. There’s a better way: interleaving.
Interleaving sounds counterintuitive. Instead of deeply studying one topic before moving to the next, you mix different topics together during study sessions. You solve an algebra problem, then a geometry problem, then a statistics problem, then back to algebra.
It’s disruptive and feels inefficient. But the research is clear: interleaving produces better learning than blocked practice.
Understanding Interleaving vs. Blocked Practice
Blocked Practice (Traditional Approach)
Study one topic thoroughly until you feel like you’ve mastered it. Then move to the next topic. Within each topic, all the problems or examples are similar.
How it feels: Smooth and efficient. You’re in the zone.
Interleaving (Mixed Approach)
Mix different topics or types of problems. You alternate between different areas within the same study session. This makes each individual study session feel less efficient because you’re constantly switching contexts.
How it feels: Choppy and challenging.
But here’s the crucial part: interleaved practice produces better long-term outcomes than blocked practice, even though blocked practice produces better performance during the practice itself.
Research That Proves It Works
The research is compelling. Studies across these domains consistently show interleaved practice outperforms blocked practice:
- Math: Problem discrimination and transfer
- Language learning: Vocabulary and grammar retention
- Sports: Athletic skill transfer
- Music: Musical performance
- Memory: Long-term retention
- Visual perception: Pattern recognition
Why Interleaving Works
The mechanism behind interleaving is something researchers call contextual interference. When you switch between topics, your brain experiences increased interference. This seems bad—more interference should mean worse learning, right?
But it’s actually the source of interleaving’s power.
How It Works
When you’re solving similar problems back-to-back (blocked practice), your brain gets into a rhythm. You see a problem and you immediately know which strategy to apply because you’ve been using the same strategy repeatedly. Your brain works on autopilot.
When you interleave topics, you can’t autopilot. Each problem might require a different approach. Your brain has to:
- Discriminate between problems
- Figure out which strategy applies
- Execute that strategy
This cognitive effort is the key to deep learning.
This discrimination between concepts is crucial. In real situations, you won’t have problems presented one topic at a time. You’ll have a mix of problems and you’ll need to know which tools to apply to which situations. Interleaving trains exactly this skill.
Specific Benefits of Interleaving
Improved Discrimination
By studying different topics side-by-side, you become better at distinguishing between similar concepts. In math, for example, you learn when to use algebra versus geometry versus statistics. This discriminatory ability is essential for real-world problem-solving.
Better Transfer of Knowledge
Knowledge learned through interleaving transfers better to new situations. If you study math topics in isolation, you might not recognize when to apply algebra to a word problem. Interleaving trains this recognition.
Stronger Long-Term Retention
While blocked practice might help you perform better on an immediate test about that single topic, interleaved learning creates stronger long-term memories that last longer.
Increased Flexibility
Knowledge from interleaving is more flexible. You can apply it to different contexts and variations. Knowledge from blocked practice tends to be narrower and more context-specific.
How to Actually Use Interleaving
Mix Problem Types in Practice Sessions
Instead of solving 20 algebra problems in a row, then 20 geometry problems, then 20 statistics problems, mix them throughout. Maybe solve problems in the order:
- Algebra
- Geometry
- Statistics
- Algebra
- Algebra
- Geometry
- Statistics
The exact order doesn’t matter as much as having variety.
Vary Subjects When Studying Multiple Classes
Don’t study one subject entirely before moving to the next. Study history for 20 minutes, then chemistry, then English literature, then back to history. This natural interleaving reduces boredom and improves learning in all subjects.
Blend Skills When Learning Physical Activities
If you’re learning guitar, don’t practice chord progressions for 30 minutes, then fingerpicking for 30 minutes, then scales. Mix them. Practice a chord progression, then some fingerpicking, then scales, then back to chords. This creates musicians who can actually perform, not just musicians who can do one skill well.
Use Digital Tools
Many flashcard and practice apps allow you to shuffle questions or topics. Spaced repetition systems often incorporate interleaving by default. Leverage these tools.
Create Study Guides With Mixed Topics
When making practice materials, deliberately mix different topics rather than organizing by topic. This forces interleaved practice naturally.
The Catch: It Feels Harder
Here’s the psychological trap with interleaving. It feels harder and less productive than blocked practice.
During a study session, blocked practice feels smooth. You’re in the zone, applying the same skill repeatedly, making progress. Interleaving feels choppy. You’re constantly switching contexts. You feel less smooth, less competent.
This discomfort is actually a sign that learning is happening. The struggle is the learning. But it’s hard to trust this when blocked practice feels more efficient.
Research shows that students often:
- Underestimate how much they learn from interleaved practice
- Overestimate how much they learn from blocked practice
- Mistake comfort and ease with actual learning
In reality, harder-feeling practice often creates better learning.
Combining Interleaving With Other Techniques
Interleaving is powerful alone, but combining it with other evidence-based methods amplifies the effect.
Use interleaving with spaced repetition: By the time you revisit a topic days or weeks later, the switching effect from interleaving helps you discriminate better between concepts.
Combine with active recall: Force yourself to identify which strategy to use before solving the problem. This additional cognitive step strengthens learning.
Add elaboration: Explain why you chose a particular strategy for each problem. Connect the problems to other concepts you know. This creates deeper understanding.
Real-World Application
Interleaving isn’t just for academic studying. If you’re learning a new skill at work, interleave different aspects of the skill rather than mastering one aspect at a time.
Language learning: Mix vocabulary, grammar, listening, and speaking practice rather than focusing on one area exclusively.
Physical skills: Like dancing or sports, mix different techniques and movements rather than perfecting one movement at a time.
Getting Started
- Pick one subject or skill you’re currently studying
- Identify different topics or types of problems within that subject
- Create a study session that mixes these topics deliberately
The first session will feel choppy and inefficient. That’s normal. Continue. After a few interleaved sessions, you’ll notice: you’re better at discriminating between concepts. You’re recognizing which tool to use in which situation faster. Your long-term retention is stronger.
The initial discomfort is worth the long-term learning improvement.
