Cardavela
You learn twenty new words on Sunday evening. By Monday morning you can recall about half. A week later, only a handful are left. That is not a sign of a bad memory; it is how memory works for everyone. Unused information fades. The useful part is that you can work with this instead of against it. Spaced repetition is a way of reviewing each word right around the moment it starts to slip. Here is what it is, what the FSRS scheduler does, and why short sessions win over long ones, without any formulas.
Forgetting is normal
In the 1880s the psychologist Hermann Ebbinghaus described what is now called the forgetting curve. Right after learning something, recall is strong, then it drops quickly, and the drop gradually slows down. He also noticed something encouraging: each time you successfully retrieve a memory, it becomes more stable, and the next decline is gentler.
Put those two observations together and you get a simple plan. Review a word after a short gap, then after a longer one, then a longer one still. Each successful review buys you more time before the next.
What spaced repetition actually is
Spaced repetition is a study method where every flashcard comes back after a calculated interval. The rules of thumb:
- If a card felt easy, the next interval grows a lot.
- If you got it but it took effort, the interval grows more cautiously.
- If you missed it, the card returns soon and the cycle restarts.
The result is that you spend very little time on what you already know well and most of your time on what is about to fade. Each review lands at the point where recalling is a bit of a stretch but still possible, which is where reviewing does the most good.
What FSRS does
Nobody wants to track intervals by hand, so a scheduler does it. Cardavela uses FSRS, the Free Spaced Repetition Scheduler, a modern open-source algorithm. In simplified terms, it keeps an estimate of three things for every card:
- Difficulty: how hard this particular item is for you.
- Stability: how firmly it is already stored.
- Retrievability: how likely you are to recall it right now.
Your answers update those estimates, and FSRS picks the next review date. There is nothing to configure. You answer honestly, and the schedule adapts.
Why short reviews beat cramming
Cramming means packing as much as possible into one long sitting, usually right before a test or a trip. It can carry you through the next day, but most of it is gone soon after, because every repetition happened in the same short window. Durable memory needs repetitions spread across time.
Short, regular sessions fit that need much better:
- They are easy to start. Five minutes is easier to find than an hour.
- Each review arrives when it is most useful, not all at once.
- Reviewing becomes a routine instead of a heroic effort.
That is why Cardavela sessions are short, up to 8 cards. It is a deliberate choice. A few small sessions over a day give memory what it actually needs: returning to the same words with gaps in between.
How it looks in Cardavela
One card fills the screen. You recall the answer, then tap to flip it and see the meaning, an example, and spoken audio from iOS speech. Then you rate yourself: swipe right for Know, left for Don't know, up for Easy, or use the Don't know, Hard and Know buttons.
That rating is the signal FSRS works from. The word lands in a Don't know, Hard or Know list and gets its next review date. The statistics screen shows how many words will come back over the week ahead, along with your streak, marks per day and a 12-week calendar.
The one rule that matters: be honest. If you tap Know on a word you did not really recall, the scheduler will push it far into the future and it will be gone by the time it returns. Honest ratings are what make the whole method work.
This applies whatever direction you study in. Whether you are a Russian speaker building English vocabulary or an English speaker working on Russian with your own deck, the scheduler only cares about one thing: did you remember?
Try spaced repetition yourself
The quickest way to understand spaced repetition is to use it for a week. Download Cardavela from the App Store and start with the Frequent words deck: no account, no ads, and it works offline. Or open the deck library and study online in your browser, with progress saved in your browser's local storage.
