Memory, Retention and Retrieval Strategies groups empirically studied techniques and effects that improve how durably material is remembered, drawn from cognitive-psychology research on learning rather than from a broad theory of mind or motivation. Belongs here: the Spacing Effect and Interleaving, which show that distributing and mixing practice over time improves retention compared to massed, blocked study; the Testing Effect, which shows that retrieval practice itself strengthens memory beyond restudying; Elaborative Interrogation, prompting a learner to explain why a stated fact is true; and Desirable Difficulties, Robert Bjork's umbrella concept that conditions making learning feel harder in the moment often produce more durable long-term retention. Does not belong here: a broad account of how memory is structured or processed, grouped under Behaviorist and Cognitive Processing Theories, and a theory of a learner's motivation to study at all, grouped under Motivation and Affective Theories, even though these strategies are often deployed to serve both.