Interleave practice across different skill types within a single session

Mix practice across multiple distinct skills in a session rather than completing all repetitions of one skill before moving to another.

Why it works

Interleaving different skills within a session creates the same reconstruction demand as varying within a skill: the learner cannot use the residue of the previous attempt because the last attempt involved a different skill. This forces the brain to retrieve each skill’s schema fresh each time it appears. Research by Rohrer and Taylor in mathematics showed that interleaved problem types produced better final test scores than blocked types, even when blocked practice produced better scores during practice.

How to do it

1. List the skills or topics you need to practice this session.
2. Create a mixed sequence: skill A, skill B, skill C, skill A, skill B, skill C — rather than A × N, then B × N.
3. For each appearance of a skill, treat it as a fresh retrieval event, not a continuation.
4. Use a shuffled card deck, a random number generator, or a pre-made interleaved problem set to enforce the mixing.

Evidence

The mathematics interleaving studies by Rohrer and Taylor (2007, 2010) directly tested blocked vs. interleaved problem sets in classroom conditions, finding 72% correct for interleaved vs. 38% for blocked on a delayed test in one study. The effect generalizes to other cognitive skills. (rct)

The interleaving benefit requires that each component skill has been introduced at least minimally beforehand; attempting to interleave completely novel skills produces confusion rather than interference.

Sources

• Rohrer & Taylor (2007), The shuffling of mathematics problems improves learning, Instructional Science

Common mistake

Creating a list of topics and working through them sequentially, which is functionally blocked practice even when it feels like variety.