# Interleaving: Why Mixing Practice Beats Blocking

Traditional advice says practice one thing until you master it, then move to the next. Research says this is backwards.

Interleaving—mixing different topics or problem types during practice—produces better learning than blocked practice, even though it feels harder.

## What Is Interleaving?

**Blocked practice:** AAAA BBBB CCCC (master one type, then the next)
**Interleaved practice:** ABCABCABCA (mix types throughout)

Example: Instead of doing 20 multiplication problems, then 20 division, mix them randomly.

## Why Interleaving Works

**Discrimination learning:** Mixing forces your brain to identify WHICH strategy applies, not just HOW to execute one strategy.

**Retrieval practice:** Each switch requires retrieving the relevant approach from memory, strengthening it.

**Spacing effect:** Interleaving naturally spaces practice of each type.

## The Research

Studies consistently show interleaved practice produces 20-50% better performance on delayed tests, despite worse performance during practice.

In one study, students learning to identify painting styles performed 30% better when training was interleaved vs. blocked.

## How to Implement Interleaving

1. **Mix problem types** in homework and practice sets
2. **Study multiple subjects** in one session rather than marathoning one
3. **Randomize flashcard order** rather than grouping by topic
4. **Combine old and new material** in each practice session

## When Interleaving Works Best

- After initial learning (you need some competence first)
- For discriminating between similar concepts
- For applying knowledge to novel situations

## It Will Feel Harder

Interleaving produces more errors during practice. This is desirable difficulty—the struggle is the learning.

Trust the research over your feelings. Long-term retention matters more than practice performance.

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- [Retrieval Practice: The Science of Remembering](https://brainrash.com/blog/retrieval-practice)
- [The Ultimate Guide to Spaced Repetition: How to Remember Anything Forever](https://brainrash.com/blog/spaced-repetition-ultimate-guide)

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