What interleaving is — and isn't

Blocked practice is what most students default to: "I'll do an hour of trigonometry, then move on to vectors tomorrow." Interleaved practice mixes them: trig, then vectors, then probability, then back to trig. Within a session, you're constantly switching between topics rather than locking onto one.

In the moment, interleaving feels worse — your accuracy drops because you keep having to re-orient. But long-term, retention and transfer improve dramatically. Studies in maths and motor learning consistently show interleaved practice outperforming blocked practice on delayed tests.

Why it works

Two reasons. First, interleaving forces your brain to discriminate between problem types — to decide "what kind of problem is this?" before solving it. That's exactly what an exam asks you to do. Second, the act of switching forces retrieval from scratch each time, which strengthens memory more than re-running a freshly-loaded routine.

The flip side: don't interleave wildly different subjects. Mix maths topics with maths topics, history events with history events. The benefit comes from discriminating between similar things, not from confusing yourself across domains.

How to interleave your revision

In a 60-minute session covering three related topics, do 5–10 mixed questions per topic in rotation rather than 20 questions of one topic at a time. Don't worry about your accuracy in the session — that's not the metric. Test yourself a week later on the same questions; that's where interleaving wins.