Interleaving

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Why it works

Interleaving, mixing different problem types or topics within a practice session rather than practicing one in a block, is a well-supported learning strategy. It improves long-term retention and, crucially, students' ability to discriminate between problem types and choose the right approach, because they must identify what kind of problem they face. It feels harder than blocked practice (a desirable difficulty), which is part of why it works.

The research: The Learning Scientists on interleaving; research on interleaved practice.

The run-of-show

Choose your slot. The agenda, timings, and length update to match.

The core activity: interleave one set of practice

Teachers leave with one blocked practice set reworked to interleave related types.

Pick practice you currently do in blocks, one type at a time.
Mix different but related problem types or topics within the practice.
Make sure students have to identify which type they face.
Explain that it feels harder because it is working.

Mix it up to tell them apartBlocked practice feels easy and fades; interleaving different types builds the ability to choose the right approach. Mix the practice, and tell students the difficulty is the point.

Facilitator notes

Mix related types within practice.
Ensure students identify the type, and expect it to feel harder.
Use once students can do each type.

Blocked practice flatters performanceMassing one type looks smooth in the moment but transfers poorly. Interleave related types so students learn to discriminate and choose.

Adapt it

Elementary: mix related skills once learned.
Secondary: interleave problem types in math, grammar, classification.
All settings: mix related types, identify which is which.

Participant handout

One page for every teacher. Print it, or save it as a PDF.

K12 Academics · Professional Learning

Interleaving: mix the practice

Harder, and better: mix related problem types so students learn to tell them apart and choose the approach.

The practice I currently do in blocks:
The related types I will mix:
How students identify which type they face:
How I explain why it feels harder:
Where interleaving will help most:

Make it stick

Mix to discriminate:

Interleave related practice.
Expect desirable difficulty.
Bring interleaved practice that helped to the next PLC.

Common questions

How is interleaving different from spaced practice?

Spacing is about time gaps between practice; interleaving is about mixing different types within a session. They complement each other, but they are distinct.

Won't mixing problems confuse students?

It feels harder, and that is the point: having to identify which type of problem it is builds the discrimination that blocked practice skips. Keep the content appropriately challenging.

Where does interleaving help most?

Where students need to tell similar problem types apart and choose the right approach (math, grammar, classification). Mix the types once students can do each.