Why spaced repetition works

Why is it so hard to remember a word you learned yesterday? It’s not your fault — it’s exactly how your brain works. The good news: there’s a proven way to turn this to your advantage.

The forgetting curve

In the late 19th century, Hermann Ebbinghaus measured how learned information fades over time. The result was striking: we lose new information fastest within the first 24 hours. Without review, almost nothing remains a week later.

Recall right before you forget

The idea behind spaced repetition is simple: show a word just as you’re about to forget it. Your brain works to retrieve it, and that effort strengthens the memory. It’s called “desirable difficulty” — a little struggle makes learning stick.

Each successful recall stretches the interval:

• Day one → next day
• Then 3 days
• Then 1 week
• Then 2 weeks, 1 month…

Get it wrong and the interval shrinks, so the word comes back more often.

YellowWhat does this for you

YellowWhat uses the SM-2 algorithm to compute the ideal review time for every word. You just spend a few minutes a day; the app knows which word to show you and when.

You don’t memorize — you recall. That difference is what lasts.

Ready for your first lesson? Open the app and get started.