Interleaving for Retention

Counterintuitively, mixing different skill types within a session, called interleaving, produces better long-term results than drilling one thing over and over. A tennis player who alternates serves, volleys, and backhands retains more than one who hits 200 serves in a row.

It feels harder and sloppier in the moment. Your brain keeps switching contexts, and that productive struggle is what cements learning. Research by Robert Bjork at UCLA found interleaved practice beats blocked practice for retention, even when learners rate it as less effective.