Similarity matters: A meta-analysis of interleaved learning and its moderators

We checked this card's citation and the finding we state against the source's own page or record in October 2026.

What it found

Interleaving had a moderate overall benefit and a small one for math tasks, and worked best for visual material such as paintings. Results for expository texts were unclear, and for learning words, blocking did better. Interleaving helped most when categories were similar to each other and the material was complex.

Effect size, as the source reports it: overall g = 0.42; mathematical tasks g = 0.34; paintings g = 0.67; words g = -0.39 (blocking better).

What kind of study it is

Design

Meta-analysis

Weight

A synthesis: it pools or weighs many studies, so it carries the most weight on the evidence meter.

Sample

59 studies, 238 effect sizes in 158 samples

Read it

doi.org/10.1037/bul0000209

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Cited in the Library

• Interleaved practice