Spaced repetition: how to memorize English words for good
Spaced repetition is the most effective method research knows for holding vocabulary long term. More than a century of cognitive psychology supports it, and it explains why one learner keeps thousands of English words while another relearns the same list every month.
If you have ever studied twenty words on a Monday and remembered five by Friday, your memory worked fine and your schedule did not.
How fast do you forget a new word?
In 1885 the German psychologist Hermann Ebbinghaus ran the first systematic experiments on memory and drew his forgetting curve, and later replications land on the same shape.
- Within 24 hours you forget about 70% of what you learned.
- Within a week more than 75% is gone.
- Without active review, little of the rest survives.
Your brain discards what it seems not to need. A word seen once, in a list, on a Tuesday, looks like noise to it. The trick is convincing it that the word matters, and the signal it understands is repeated recall, spaced over time.
How the method beats the curve
Each time you retrieve a word just before forgetting it, the memory trace strengthens and decays more slowly. Instead of reviewing ten times in one evening, you review once today, then at growing intervals.
- 1st review: 1 day after learning
- 2nd review: 3 days later
- 3rd review: 7 days later
- 4th review: 14 days later
- 5th review: 30 days later
- 6th review: 90 days later
Answer correctly and the interval stretches. Hesitate or fail and the word comes back sooner. Five or six well-placed reviews, a few seconds each, are enough to move a word into long-term memory. The same total effort packed into one evening produces a memory that lasts days instead of years.
Test yourself instead of rereading
The second ingredient is active recall. Rereading a vocabulary list feels productive because the words look familiar, but recognising is not retrieving. Testing yourself, reaching for the word before seeing the answer, is measurably more effective. Researchers call it the testing effect. Flashcards work because they force that attempt.
What changes when you apply it to English
- Audio on every card. English spelling is a poor guide to pronunciation, as though, through and tough show. Hearing the word as you learn it builds listening comprehension at the same time.
- Words by frequency. Reviews cost time, so spend it on what appears most. The first thousand words cover 85% of everyday English.
- Varied exercises. Meeting the same word as a card, in a quiz and typed from memory creates several retrieval paths and avoids the mechanical feel.
The practical problem: nobody keeps that schedule by hand
Spaced repetition has one weakness. With hundreds of words in rotation, each carrying its own review date, the bookkeeping becomes impossible on paper. That is what English Progress automates. The app follows every word you learn, places its reviews at the right intervals and shows you what is due today, usually five minutes. You bring the five minutes; the algorithm brings the schedule.
The words that keep coming back
Every learner accumulates a handful of words that fail review after review. Spaced repetition calls them leeches: they take a disproportionate share of your sessions and never settle. Two things cause it. The word has no hook, so nothing in your memory holds it. Or it sits too close to another word you already know, and the two keep swapping places.
The fix is not more repetitions. Give the word a context you own: a sentence from a series you watched, a colleague who says it, an image. If it still fails after that, suspend it and come back in a few months. A word you meet at 3,000 will often stick on its own once the surrounding vocabulary is in place.
What happens when you skip a week?
Missing days is the normal case, not the exception. The schedule handles it, on one condition: do not restart from zero. A word due on Monday and reviewed on Friday is still a valid review, and the algorithm reads the delay as information about how long the memory held.
The backlog breaks people. Come back after three weeks and you face several hundred cards at once, which is discouraging enough to end the habit. Cap the session instead: clear fifty cards a day until the queue drains. The order is already sorted by urgency, so the fifty you do are the fifty that matter most.
How long should a session run?
Five minutes covers ten new words plus the reviews they trigger. Push to twenty minutes and the last words of the session land in a tired brain, which costs you extra reviews later. The ceiling is not your willpower, it is how many fresh items your memory files in one sitting.
The number that scales is new words per day, not minutes. Ten a day is sustainable for years and reaches 3,000 inside a year. Thirty a day feels productive for a fortnight, then the review load triples and the schedule collapses under its own weight.
Sources
- Henry L. Roediger III & Jeffrey D. Karpicke, Test-Enhanced Learning: Taking Memory Tests Improves Long-Term Retention, Psychological Science 17(3), 2006, pp. 249-255.
- Hermann Ebbinghaus, Memory: A Contribution to Experimental Psychology (1885), English translation, Classics in the History of Psychology, York University.
- I.S.P. Nation, How Large a Vocabulary Is Needed For Reading and Listening?, Canadian Modern Language Review 63(1), 2006, pp. 59-82.
English Progress schedules your reviews. You bring the 5 minutes.
