Most learners forget a new word within days of meeting it. That is not a personal failing — it is how human memory works. The good news is that the forgetting is predictable, and once you can predict it, you can schedule around it.
Why cramming fails
Memory has two jobs: storing information and retrieving it later. Re-reading a word list strengthens the feeling of familiarity, but it barely improves retrieval. This is why a word can feel “known” while you read a list and then vanish the moment you need it in conversation.
The fix is retrieval practice: forcing your brain to pull the answer out instead of recognising it. Every successful recall also makes the next recall easier — a phenomenon called the spacing effect.
What spaced repetition actually does
A spaced repetition system (SRS) tracks every item you study and shows it again right before you would otherwise forget. Two variables decide each review:
| Variable | What it controls | Example |
|---|---|---|
| Interval | How long until the next review | 1 day → 3 days → 8 days |
| Ease | How fast the interval grows | Hard words grow slowly, easy words quickly |
When you recall a card successfully, the interval expands. When you fail it, the interval collapses and the word returns within minutes or hours.
FSRS: the modern scheduling algorithm
Older systems such as SM-2 used a fixed multiplier and a handful of grades. FSRS (Free Spaced Repetition Scheduler) instead models three properties of every card:
- Difficulty — how hard this item is for you
- Stability — how long the memory will survive before recall drops
- Retrievability — how likely you are to recall it right now
Because FSRS estimates the probability of recall, it can choose the moment when that probability has dropped to a target level, usually around 90%. The result is fewer reviews for the same retention, and shorter intervals for words you already find easy.
The goal of spaced repetition is not to study more. It is to study at exactly the moment when studying pays off the most.
Putting it into practice
- Make cards that test one thing. A card asking “what does resilience mean?” is stronger than a card asking five questions at once.
- Answer before you flip. Even a wrong guess strengthens memory more than passive reading.
- Let the algorithm drive. Grade honestly — “again” for a blank, “easy” only when recall was instant.
- Keep sessions short and frequent. Ten minutes a day beats two hours on Sunday.
- Study in context. Add an example sentence to every card so the word is learned with the grammar it lives in.
A realistic schedule
For a goal of roughly 20 new words per day, expect the daily review load to level off at a few hundred cards after the first month. Reviews are the price of fluency — and because spaced repetition spreads them out, the per-word cost keeps falling.
If you would rather not manage intervals by hand, EnjoyCards applies FSRS automatically: create a card, review it, and the app decides when you should see it next.