Spaced repetition explained: how to stop forgetting words

The forgetting curve

In the 1880s Hermann Ebbinghaus measured how fast he forgot nonsense syllables. Memory drops steeply in the first day and then levels off. Every review resets the curve and makes it flatter, which is why the second review can wait longer than the first.

How a spaced-repetition schedule works

1. You learn a word.
2. It comes back the next day. If you recall it, the gap grows (3 days, then a week, then longer).
3. If you miss it, the gap shrinks and it comes back soon.

Over a few weeks most words move to long gaps and only the hard ones keep showing up.

Make reviews fast and active

• Recall, don't recognise: try to produce the meaning or the word before seeing options
• Keep it short: a minute of fast reviews daily beats a long weekly session
• Hear and say the word, not just read it

Vocavoy's 60-second Vocab Sprint is a spaced-repetition review: it serves the words due today, and a separate Weak Words drill brings back the ones you keep missing.