Testing yourself on material beats re-reading it, even if it feels less productive
Henry Roediger and Jeffrey Karpicke had students study a passage, then either re-read it repeatedly or try to recall it from memory. A week later, the students who had quizzed themselves remembered far more than the re-readers, despite feeling less confident about their own learning at the time. Actively retrieving information strengthens memory in a way that passive review doesn't.