What it says. Retrieving information from memory strengthens it more than rereading does, a finding often called the testing effect. Spacing practice over time produces more durable learning than massing it in one session. Both feel harder than rereading, and that difficulty is part of why they work.

What it means for your teaching. Use frequent low-stakes retrieval: a quick question at the start of class, ungraded quizzes, brief writing from memory. Revisit key ideas across the term rather than only in the unit where they first appear. Tell students that cramming feels productive but spaced retrieval is what lasts, since many will not know it.