Interleaving is a study strategy in which you mix different topics or types of problems in a single session, instead of practising one type at a time in a block.
How it works
In a typical textbook chapter, every practice question uses the method you just learned. That makes practice feel smooth, but it hides a key skill: recognising which method a problem needs. Exams do not tell you that a question is about the chain rule or about a particular type of logical flaw. Interleaving forces you to make that choice on every problem.
Interleaving also builds in a little spacing, because each problem type is revisited after a gap, and it helps you notice differences between similar concepts. Seeing two easily confused ideas side by side makes the features that separate them stand out.
Interleaving usually feels harder than blocked practice, and performance during practice is often worse. That is expected: it is one of the desirable difficulties that slow learning down in the moment but improve what you remember and can apply later.
How to use interleaving (steps)
- Learn each method first. Make sure you can do each problem type on its own.
- Build mixed sets. Combine problems from several related topics into one set, in random order. Past papers and mixed practice tests are naturally interleaved.
- Identify before solving. For each problem, decide which concept or method it needs before you start working.
- Check the choice, not just the answer. When reviewing, note whether you picked the right method.
- Mix concepts in flashcard decks. Shuffle cards from related topics together rather than reviewing one chapter at a time.
- Keep spacing too. Combine interleaving with spaced repetition so older topics keep returning.
Evidence
Rohrer and Taylor (2007) found that students who practised mixed maths problems, calculating the volumes of different solids, performed considerably better on a delayed test than students who practised the same problems in blocks, even though the interleaved group did worse during practice. Kornell and Bjork (2008) found that people learned to recognise artists’ painting styles better when paintings by different artists were interleaved than when each artist’s paintings were shown together, while most participants believed blocking had helped them more. A 2019 meta-analysis by Brunmair and Richter found an overall benefit for interleaving, strongest for material where the categories are similar and easy to confuse. Dunlosky and colleagues (2013) rated interleaved practice as moderate utility, noting promising evidence mostly from maths and category learning.
Using interleaving with Duetoday
In Duetoday you can generate a practice test from notes covering several lectures at once, which produces a naturally mixed set of questions. Combine flashcard decks from related topics and review them together with spaced repetition. When you keep choosing the wrong method, ask Galileo to explain the difference between the two concepts using your own notes.
