In the 1880s, the German psychologist Hermann Ebbinghaus years memorizing lists of syllables and himself. He that we forget new information quickly at , and then slowly. pattern is known as the forgetting .

Two simple strategies can slow forgetting. The is spacing: material several over days or weeks of in one long session. The is retrieval : trying to information memory, for example answering questions, rather than rereading notes.

Most students prepare for exams by rereading their notes and textbooks. It feels productive: the material becomes familiar, and familiarity feels like understanding. Research, however, suggests that this sense of mastery can be misleading.

In a well-known 2006 experiment, students read short passages and then either studied them again or took practice tests in which they wrote down everything they could remember. When tested five minutes later, the students who had restudied performed slightly better. But one week later, the result reversed: the students who had practiced recalling the material remembered considerably more.

Psychologists call this the testing effect. Each act of retrieval appears to strengthen the memory and make it easier to access later. The effort involved is part of the benefit: struggling to recall something, even unsuccessfully, can improve later learning.

The practical lesson is simple. Instead of rereading, students can close the book and try to explain the ideas from memory, use flashcards, or answer practice questions, and then check what they missed.

Cramming, or studying intensively just before an exam, is common among university students. It can produce acceptable results on the test, but much of what is learned this way is quickly forgotten.

Spacing offers a more durable alternative. When study sessions are spread over time, each review comes after some forgetting has begun. Remembering at that point requires more effort, which, as with retrieval practice, seems to strengthen memory. Studies across many subjects, from vocabulary to mathematics, have found that the same total study time produces better long-term retention when it is spaced.

The best gap between sessions depends on how long the information needs to be remembered. For an exam in a week, reviewing after a day or two may work well; for knowledge needed for years, longer intervals are more effective.

Combined with sleep, which helps consolidate memories, spacing and retrieval practice form a powerful set of tools. Together, they suggest that how students study can matter as much as how long they study.