Spaced Repetition (SRS): Turning Vocabulary Drills Into a Daily Habit

Spaced repetition (SRS) is a memorisation method where each review of a word or fact is scheduled for the moment you’re about to forget it, with the gap between reviews growing over time. It’s the principle behind SRS vocabulary trainers: instead of cramming everything at once, a learner only reviews what’s currently closest to slipping away.

Almost every learner knows the feeling. The night before a lesson you memorise twenty new words, rattle them off confidently in class, and your teacher is impressed. A week later, five of those twenty are still in your head. The rest have quietly evaporated.

That’s not laziness and it isn’t a “bad memory”. It’s how everyone’s brain works, without exception. The good news: forgetting has been studied for well over a century, and you can work with it instead of against it. That’s the whole idea behind spaced repetition — often shortened to SRS, a spaced repetition system.

The forgetting curve: why knowledge leaks

Back in the 1880s, the German psychologist Hermann Ebbinghaus ran a simple experiment on himself. He memorised lists of nonsense syllables and tested how much he could recall an hour later, a day later, a week later. Out of that came the forgetting curve — a graph showing how quickly new information slips away when you don’t revisit it.

The shape of that curve is the surprising part. We forget the most not over a week, but in the first hours and the first day after learning. By the next day, with no review at all, only thirty to forty percent of brand-new material is still there. After that the decline slows, but the trend is relentless: anything you don’t revisit eventually disappears.

And here’s the detail that the whole method hinges on. Every well-timed review flattens the curve. Review a word after a day and you start forgetting it more slowly. Review it again three days later and the curve flattens further. Each pass sets the word a little deeper, which means the gap before the next review can safely grow: first a day, then three days, then a week, two weeks, a month.

That’s the entire idea in one sentence: review a word at the exact moment you’re about to forget it — not earlier (a waste of time) and not later (you’ve already lost it and have to relearn from scratch).

Why does cramming lose?

The classic student move is to learn everything the night before a test. Sometimes it works: the next morning you really do remember it all. But a week later almost nothing remains — and the forgetting curve explains exactly why.

Cramming loads information into short-term memory. It holds data beautifully for a few hours — just long enough to pass the test — and dumps it just as easily. The problem is that a living language needs not short-term but long-term memory: the word has to be available six months from now, when you bump into it in a real conversation.

The move from “fast” memory to “deep” memory only happens through reviews spread out over time. Psychologists call this the spacing effect, and it’s one of the most robustly confirmed findings about how humans learn. Five short ten-minute sessions across a week produce a far sturdier result than one hour-long session on Sunday — even when the total time is identical.

The paradox is that cramming feels more effective. When you run through the same words for the tenth time in a row, they come easily, and your brain happily reports: “I know this.” That sense of fluency is misleading. Real learning is slightly uncomfortable: it asks for a small effort to recall a word right as it starts to fade. That effort isn’t a bug, it’s the mechanism. Psychologists call it “desirable difficulty”: an easy review barely cements anything, whereas something you had to reach for tends to stay.

What it looks like in practice

An SRS trainer takes all of that theory off your hands, so the learner never has to calculate anything. In practice it works roughly like this.

Cards. Each word or phrase is a card: a prompt on one side, the answer on the other. The learner looks at the word, tries to recall the translation or meaning, then rates themselves honestly: “knew it” or “didn’t”.

The algorithm. Based on that answer, the app schedules the next showing. Recalled it easily? The interval grows — you won’t see the word tomorrow, but in three days. Hesitated or got it wrong? The word comes back soon, while it’s still near the surface. So every card lives at its own pace: hard words cycle often, easy ones barely bother you.

A daily batch. Instead of “learn this chapter”, the learner gets a small deck each day — the cards that are due for a nudge today, plus a few new ones. Five to fifteen minutes and you’re done for the day. Tomorrow the algorithm assembles a fresh batch.

One small touch that quietly matters a great deal is audio. Seeing a word written and hearing how it sounds are two different memory channels. For a language, pronunciation is critical: learning a word by sight and failing to recognise it by ear is a classic trap. That’s why in the Mimiao trainer the vocabulary cards come with audio, so the learner ties spelling to sound from the very first encounter.

The hard part isn’t the algorithm — it’s the habit

This is where the real catch of spaced repetition hides. The method itself works flawlessly — but only as long as the learner comes back every day. And that turns out to be the hard part.

Any algorithm is helpless if the deck goes untouched for a week. Worse, SRS can then turn against the learner: skip a few days and a mountain of overdue cards is waiting, you open the trainer, see “due: 180”, and your heart sinks. That’s the classic burnout from accumulated debt.

So in a good trainer the technical engine is only half the job. The other half is helping the learner not give up:

• Small batches. The daily deck has to feel manageable. Ten minutes every day beats cramming an hour once a week.
• Gentle reminders. A short “your cards are waiting” nudge at the right moment is often the tiny thing that saves a streak.
• Visible progress. A run of days in a row, a count of words mastered, a little celebration for finishing the batch — these aren’t childish gimmicks, they’re fuel for the habit. Visible results are what bring you back tomorrow.
• Forgiving the gaps. If a learner drops off for a few days, the trainer should ease the debt back in — mixing overdue cards in gradually rather than dumping all of them at once.

That’s precisely why in Mimiao the vocabulary trainer sits right next to the gamification: coins, levels and streaks aren’t decoration but a way to sustain that same daily habit, the one thing without which any SRS is pointless.

What to take away

Boiling it all down to a few points:

• Forgetting is normal, not a flaw. Information leaks for everyone, and it does so predictably.
• Cramming fills short-term memory and empties it just as fast. A living language needs the long-term kind.
• The secret is well-timed reviews with growing intervals: a day, three days, a week, a month.
• An SRS algorithm handles that scheduling for you — all the learner has to do is open the deck each day.
• And the genuinely hard part is exactly that daily-ness. Which is why a trainer needs small batches, reminders and visible progress around it.

Ten minutes a day, spread out over time, ultimately beat an hour of cramming before a lesson — and that’s not a question of willpower but of the right rhythm. If you’d like to see how the vocabulary trainer itself works, with audio and spaced reviews, take a look at the vocabulary trainer features page; for how it ties into gamification and the daily-practice habit, see the student engagement page.