Interleaving

Interleaving means mixing different types of problems or topics during practice, instead of doing all of one type before moving to the next. Instead of 10 addition problems then 10 subtraction problems, students do a mixed set: add, subtract, add, subtract, multiply, add... The mixing forces the brain to figure out WHICH strategy to use, not just HOW to use it.

Blocked practice (all one type) feels easier and produces better performance during practice. But on the test, interleaved practice wins every time. Why? Because blocked practice lets students auto-pilot -- they know every problem is addition, so they stop thinking. Interleaving forces them to identify the problem type each time, which builds the discrimination skill needed for real tests and real life.

Based on the interleaving effect (Rohrer & Taylor, 2007). The benefit comes from two mechanisms: (1) comparison -- seeing different types together helps students notice differences, and (2) retrieval -- switching topics forces the brain to retrieve the appropriate strategy each time, which strengthens memory.

Based on the interleaving effect (Rohrer & Taylor, 2007). The benefit comes from two mechanisms: (1) comparison -- seeing different types together helps students notice differences, and (2) retrieval -- switching topics forces the brain to retrieve the appropriate strategy each time, which strengthens memory.

Use interleaving for math (mix problem types), science (mix concepts), grammar (mix rules), or any subject where students must discriminate between different problem types. Best for review and practice sessions, not initial learning.

Avoid interleaving when first teaching a new skill -- students need blocked practice to get the basics. Also avoid if the topics are too different and students get confused. Don't interleave everything at once -- start with 2-3 related types.

Grades Grade 4 to Grade 12

Math, Science, English, and more

• Produces better retention and transfer than blocked practice
• Builds discrimination skills -- knowing WHEN to use a strategy
• Mirrors real exams where problem types are mixed
• More engaging than repetitive blocked practice
• Works for any subject with multiple problem types

• Feels harder than blocked practice -- students and parents may complain
• Requires students to have basic mastery first -- not for beginners
• Needs careful selection of which topics to interleave
• Can frustrate students who are still shaky on individual skills
• More complex to design than blocked worksheets

• Interleaving before students have mastered individual skills
• Mixing too many types at once
• Not debriefing the discrimination process
• Using interleaving for initial instruction
• Not explaining to students why it feels harder but works better

Vary the game format, question types, and team structures to maintain engagement across multiple review sessions.

This strategy requires no technology. If desired, enhance with digital tools such as Google Docs for collaborative writing or Padlet for sharing responses.

Assess through observation of participation, quality of review, and formative checks such as exit tickets or quick writes.

• Rohrer, D., & Taylor, K. (2007). The Shuffling of Mathematics Problems. Journal of Educational Psychology, 99(3), 543-552.