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Interleaving: Practice Choosing the Right Method

Mix familiar problem types so you practice choosing a method, not just repeating one.

Two rows of practice cards: one groups matching problem types together, while the other alternates different types.

Use this

  • Learn each method before mixing problem types.
  • Mix types within the same practice session.
  • Choose a method before solving each problem.
  • Expect mixed practice to feel harder than blocks.

What interleaving means

Interleaving means mixing problem types in one session instead of finishing every problem of one type before moving to the next. Use it to practice deciding which method a problem needs.

Dunlosky, Rawson, Marsh, Nathan, and Willingham (2013) rated interleaved practice as moderate utility. Treat it as a study option for familiar methods, not a replacement for learning those methods first.

Start with methods you already know

Before making a mixed set, check that you know how to use each method on its own. You need procedures to choose between.

If you do not yet know how to carry out a method, practice it separately first. Add that problem type to your mixed session once you have a procedure you can use.

Index cards spread on a desk.
Photo by Kelsy Gagnebin on Unsplash

Make a mixed practice set

Choose problems from several types you have learned. Arrange them so you move between types rather than completing a whole group of one type first.

For each problem, decide which method to use before you start solving. Ask yourself, “What in this problem tells me which method fits?” The task is to choose the procedure as well as carry it out.

Do not judge the session by how smooth it feels

Blocked practice feels smoother because you already know which method to use. Mixed practice asks you to make that choice, which is closer to what a test asks you to do.

Expect the mixed session to feel harder. If you know the individual methods, the difficulty of choosing between them is part of the work, not a reason to return to blocks. If you have no procedure to choose, learn that method before mixing it in.

Your plan for this week

Today, choose a topic with several problem types. Check which methods you can already use, and practice any unfamiliar method separately.

At your next study session, gather problems for the methods you know and mix their order. Before solving each one, name the method you will use and identify what makes it fit.

Later this week, do another mixed session. Keep choosing a method problem by problem rather than arranging the work into blocks.

At the end of the week, identify any method you still do not know how to carry out. Practice it separately before including it in your next mixed set.

Sources

These notes describe published study methods. They are not a promise about a grade.