Interleaving — Why Mixing Topics Works Better

Here is a scenario most students will recognise. You are revising mathematics. You open the textbook to the chapter on quadratic equations, and you practise twenty quadratic equation problems in a row. Then you move to the chapter on simultaneous equations and practise twenty of those. Then twenty trigonometry problems.

This approach — practising one type of problem before moving on to the next — is called blocked practice, and it is how most textbooks, most teachers, and most students organise revision.

It feels logical. It feels efficient. And it is significantly less effective than the alternative.

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What Is Interleaving?

Interleaving means mixing different types of problems or topics within a single study session, rather than grouping them into blocks.

Instead of: AAAA BBBB CCCC (blocked)

You do: ABCB CACB ABCA (interleaved)

With interleaving, you might solve a quadratic equation, then a trigonometry problem, then a simultaneous equation, then back to quadratics — all shuffled together in a single session.

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The Research on Interleaving

The Rohrer & Taylor (2007) Study