Spaced Repetition: How to Remember What You Learn

You learn something today, feel confident, and a week later it's gone. That's not a personal failing — it's how memory works. Spaced repetition is the technique built specifically to beat it.

The forgetting curve

Over a century ago, Hermann Ebbinghaus mapped how fast we forget: memory of new material drops steeply within the first days, then keeps fading. Cram it all in one night and most of it leaks out before the exam.

But there's a catch that makes everything better: each time you review just before forgetting, the curve gets flatter. The memory decays more slowly after every well-timed review. Do this a handful of times and the fact becomes nearly permanent.

What spaced repetition does

Instead of reviewing everything every day (exhausting) or once and never again (useless), spaced repetition spaces your reviews out at growing intervals — a day, then three, then a week, then a month. Each review comes right as the memory is about to slip, which is exactly when reinforcing it does the most good.

The result: you spend less total time reviewing and remember more, because you're never wasting effort on things you already know well, and never leaving things long enough to lose them.

How to use it

• Review by difficulty, not by schedule-for-everything. Cards you find easy should come back rarely; ones you keep missing should come back soon. The interval should depend on how well you knew it.
• Short daily sessions beat long weekly ones. Ten minutes a day, hitting only what's due, is far more effective than a three-hour weekend block.
• Pair it with active recall. Spacing decides when you review; active recall decides how — always test yourself, don't reread.
• Start early. Spaced repetition needs spacing, which needs time. It's the opposite of cramming, so it only works if you begin well before the exam.

Cramming trades a week of panic for a month of forgetting. Spacing trades ten minutes a day for memory that lasts.

The reason people don't do it

Managing intervals by hand is a nightmare — you'd need to track when every fact is next due. That's why spaced repetition lived in niche flashcard apps for years. Sinau does the scheduling for you: save any study pack and it turns the material into review cards, then surfaces each one exactly when it's due. Open the review tab for a few minutes a day and the algorithm handles the timing. That's the whole point — you just show up.