Using interleaved practice to foster spelling acquisition

Interleaving exemplars from different categories tends to improve category learning compared to blocking the same exemplars. However, the effectiveness of interleaving is uncertain when verbal materials are employed for learning. Moreover, research on interleaving in real educational settings and in the context of spelling instruction is scarce. We report the results of a preregistered classroom experiment ( https://aspredicted.org/BZH_BTC ) that examined the benefits of interleaving for learning spelling rules. The study involved 108 German third graders. Children received two training sessions in which they practiced words associated with specific spelling rules (i.e., capitalization, single and multiple consonants, or words with “i” and “ie”), with one session following a blocked and the other an interleaved format. Learning outcomes were measured shortly after the training and after 8 weeks to gauge effects of interleaving on lasting learning. Children showed fewer spelling errors when they practiced exemplars in an interleaved than a blocked sequence for words trained in the sessions. This interleaving benefit persisted after an 8-week follow-up for the trained and new words for children with average to high prior knowledge of word spellings. Children made more spelling errors during the interleaved compared to the blocked practice phase, perceived interleaved practice as more difficult, and rated their learning process as less successful compared to blocked practice, supporting the assumption that interleaved practice is a desirable difficulty. Interleaved practice is a promising approach to boost the acquisition of spelling rules, particularly among children with better prior knowledge. • Third graders benefit from interleaved practice to learn similar spelling rules. • Better spelling performance was also evident in a transfer task. • Interleaved practice promotes lasting knowledge. • Interleaving benefit was highest in children with prior knowledge of word spellings. • Metacognitive judgments indicate interleaving as a desirable difficulty.