Interleaving was found to be of greatest use when differences between items are subtle, and the benefit extended to both art- and science-based items, with implication for practitioner decisions over how and when to apply the technique. Memory (as tested by presenting studied items from a learned category) showed an interleaving benefit with effect sizes (Hedges’ g) of up to 0.65, and transfer (as tested by presenting novel items from a learned category) a benefit with effect sizes of up to 0.66. A total of 26 studies met the inclusion criteria a subset of 17 studies (with 32 constituent datasets) formed the basis of a meta-analysis, and the remainder were analysed within a narrative review. This concept has important implications for how and when teachers present examples in the classroom. A systematic review was conducted into the effect of interleaving the order of examples of concepts in terms of both memory of items and transfer to new items.
