The best way to study and retain information is to actively test yourself on the material rather than passively re-reading it. Students who quiz themselves after learning retain roughly 80% of the material, compared to just 30% for those who only review their notes. That single shift, from reading to retrieving, is the most powerful change you can make. But several other techniques stack on top of it to push retention even higher.
Why You Forget So Quickly
Your brain starts discarding new information almost immediately. Hermann Ebbinghaus documented this in the 1880s, and modern replications confirm the pattern: within one hour of learning something, you’ve already lost more than half the ease of recalling it. After a day, retention drops further. After six days, you’re holding onto a fraction of what you originally learned. This isn’t a flaw in your brain. It’s a filtering system designed to discard information that doesn’t seem important, and the way you study is what signals importance.
The good news is that every technique below works by exploiting how this filtering system operates. When you force your brain to retrieve a piece of information, or when you revisit it at strategic intervals, you’re essentially telling your memory system: keep this.
Active Recall Beats Re-Reading Every Time
Re-reading your notes or highlighting a textbook feels productive. You recognize the material, and that familiarity tricks you into thinking you know it. But recognition is not the same as recall. The real test of learning is whether you can produce the answer from memory without looking at it.
This is called the testing effect: the act of retrieving information from memory strengthens the memory itself. In controlled experiments, students who took practice tests (even without receiving feedback on their answers) dramatically outperformed students who spent the same amount of time re-studying. The difference was especially stark on delayed tests given days or weeks later. Re-studying actually produced better results on a quiz given five minutes afterward, but testing produced substantially greater retention over time. So if you’re studying for anything beyond tomorrow morning, self-testing wins.
Practical ways to do this include closing your book and writing down everything you remember, using flashcards, answering practice questions, or simply pausing after each section and asking yourself “What did I just learn?” The discomfort of not being able to remember something is the point. That struggle is what builds the memory.
Space Out Your Review Sessions
Cramming everything into one long session is one of the least effective ways to build lasting memory. Spaced repetition, spreading your review across multiple sessions over days or weeks, consistently produces better long-term retention.
The optimal spacing depends on when you need the information. If you need to perform well on a test in the near term, daily sessions work best. If you need to retain knowledge over months or years (for a career, a language, or cumulative coursework), reviewing on alternate days or with gradually increasing gaps produces stronger long-term results. A good starting framework: review new material the same day you learn it, then again after one day, then after three days, then after a week. Flashcard apps like Anki automate this schedule for you, adjusting intervals based on how easily you recall each card.
The key insight is that some forgetting between sessions is actually helpful. When you let yourself partially forget and then successfully retrieve the information, the memory trace gets reinforced more strongly than if you’d never forgotten at all.
Mix Up Your Subjects
Most students practice in blocks: all the algebra problems, then all the geometry problems, then all the statistics problems. This feels logical, but it produces weaker learning than interleaving, which means mixing different topics or problem types within a single study session.
In a study of undergraduate physics students, those who practiced with interleaved assignments scored 50% higher on a surprise test covering the first half of the course and 125% higher on a test covering the second half, compared to students who practiced in the traditional blocked format. Interleaving improved both their ability to remember relevant information and their accuracy in solving novel problems they hadn’t seen before.
Interleaving feels harder in the moment. Students who use blocked practice often feel more confident, and their homework scores may even look better. But when it comes time to apply knowledge flexibly on an exam or in real life, interleaved learners consistently outperform. The difficulty of switching between topics forces your brain to identify what makes each concept distinct, which deepens understanding.
Combine Words With Visuals
Your brain processes verbal information and visual information through two separate systems. When you encode something using both channels, you create two independent pathways to the same memory, which makes it easier to retrieve later. This principle, known as dual coding, is why a diagram with a brief explanation tends to stick better than either the diagram or the explanation alone.
You can apply this by drawing simple sketches of concepts, creating diagrams or flowcharts, mapping out relationships visually, or pairing vocabulary with images. The visuals don’t need to be artistic. A rough sketch of a biological process or a hand-drawn timeline is enough to activate that second memory channel.
Use the Feynman Technique for Deep Understanding
Named after the physicist Richard Feynman, this four-step method is particularly useful when you’re struggling with a complex topic and can’t tell whether you truly understand it or are just memorizing words.
- Study the topic thoroughly. Read, take notes, and engage with the material as you normally would.
- Teach it to someone else. Explain the concept out loud as if your listener has no background in the subject. A real person is ideal because they’ll ask questions, but talking to an empty room works too.
- Identify and fill the gaps. The places where you stumbled, used vague language, or couldn’t answer a question reveal exactly what you don’t understand. Go back and study those specific weak spots.
- Simplify your explanation. Strip away jargon and compress the concept until you could explain it to a child. If you can do that, you genuinely understand it. If you can’t, you have more gaps to fill.
This technique works because it forces retrieval, exposes the illusion of understanding that passive reading creates, and pushes you toward the kind of deep comprehension that resists forgetting.
Keep Sessions Under Four Hours
Studying for more than four hours in a single day is associated with significantly increased mental fatigue, and that fatigue can carry over into the following day. Research on medical students found that sessions of up to four hours didn’t increase fatigue compared to not studying at all, but exceeding that threshold led to a buildup that impaired the next day’s capacity. Even one to two hours of demanding study was associated with increased distress the following day if recovery time wasn’t adequate.
This doesn’t mean you should always study for four hours. Shorter, focused sessions of 25 to 50 minutes with brief breaks in between tend to maintain concentration better than marathon stretches. The four-hour mark is more of a ceiling for total daily study time before diminishing returns set in. If you’re studying beyond that point, you’re likely encoding less and fatiguing more. Better to stop, rest, and return tomorrow, which also gives spaced repetition a chance to work.
Sleep Is Not Optional
Sleep is when your brain physically moves new memories from temporary storage into long-term networks. During deep sleep specifically (not dream sleep), the brain replays recently learned information and gradually transfers it from the hippocampus, which acts as a short-term holding area, to the broader networks of the cortex for permanent storage. This process, called system consolidation, appears to happen preferentially during sleep because it would interfere with the brain’s ability to process incoming information while you’re awake.
Cutting sleep to gain more study hours is counterproductive. You’re skipping the biological process that makes studying worthwhile in the first place. Studying before bed can actually be strategic, since the material is fresh when consolidation begins.
Forget About “Learning Styles”
The idea that you’re a “visual learner” or an “auditory learner” and should tailor your study methods to match is one of the most persistent myths in education. Despite over 70 different classification instruments for sorting people into learning styles, the scientific consensus is clear: there is no evidence that matching teaching methods to a student’s preferred style improves learning outcomes. You may have preferences for how you like to receive information, but those preferences don’t predict how effectively you’ll retain it.
What does work is using multiple modes of input (visual, verbal, hands-on) for the same material, regardless of your supposed style. That’s dual coding in action, and it benefits everyone, not just “visual learners.” So rather than limiting yourself to one channel, use all of them.
Putting It All Together
A practical study session built on these principles looks something like this: you read a section of material, close the book, and write down or say aloud everything you can remember. You check what you missed and focus on those gaps. You mix in review of older material from different topics rather than drilling one subject in isolation. You sketch diagrams or create visual summaries alongside your notes. You keep the session to a reasonable length, take breaks, and plan to revisit the material in a day or two rather than cramming it all today. And you protect your sleep.
None of these techniques require special tools or apps, though flashcard software can help automate spacing. What they do require is a willingness to embrace difficulty. The methods that feel easiest, like re-reading and highlighting, produce the weakest retention. The ones that feel effortful, like testing yourself, mixing topics, and simplifying complex ideas until a child could follow, are the ones that actually work.