Spaced repetition means reviewing each fact just before you would forget it, so every successful review pushes the next one further out. FSRS, the Free Spaced Repetition Scheduler, is an algorithm that picks that moment, and Anki among other flashcard apps offers it. It keeps two numbers for every card, how stable your memory of it is and how hard it is for you, and schedules the next review for when your chance of recalling it drops to about 90 percent.
If you have ever crammed the night before an exam, done fine, and two weeks later could not explain the material to anyone, you have met the problem spaced repetition solves.
Why is forgetting predictable, and why does that matter?
Memory researchers have known for over a century that forgetting follows a curve: sharp right after you learn something, then leveling off. The useful part is what happens when you review something just before you would have forgotten it. Each successful review at that point makes the next gap longer.
Review too early and you spend time on something you still remember. Review too late and you relearn it almost from scratch, which is nearly as slow as learning it the first time. Spaced repetition turns this into a system: instead of guessing when to review, an algorithm tracks each fact and tells you when it is close to the edge.
A large 2013 review of study techniques in Psychological Science in the Public Interest rated spaced practice and practice testing as the two most useful methods it examined, and rereading and highlighting among the least. Flashcards on a spaced schedule are both at once.
In Scholarwire, every deck runs on FSRS with a 90 percent target, and the Study page says how many cards there are to review today. You can start free, then make a deck from your notes with AI credits or import one from Quizlet, Anki or a CSV file.
What is FSRS?
FSRS is an open, published algorithm that decides when each flashcard should come back. Anki, one of the most widely used flashcard apps, offers it as an alternative to SM-2, the older method it used for years.
The difference matters in practice. SM-2 gave every card one number, an "ease factor", that moved up or down a little after each review. FSRS tracks two things for every card instead:
- Stability, roughly "how many days can pass before I am likely to forget this".
- Difficulty, roughly "how hard is this fact for me, whenever I learned it".
Because these are separate, FSRS can tell a hard fact you have reviewed often enough to hold for a while from an easy fact you have seen once, which is still fragile. One ease number cannot make that distinction.
Why does FSRS aim for 90 percent?
It is a trade-off. Aiming for 99 percent recall would mean reviewing constantly, spending time on facts you already know cold. Aiming for 50 percent would save review time and mean forgetting half of what you review. Ninety percent is the default Anki's manual describes as a good balance between how much you retain and how much you review.
This is also why forgetting a card now and then is not a sign anything is broken. At a 90 percent target, about one review in ten is expected to be a miss. That is the system working as designed.
How do my ratings change the schedule?
Most review screens give you rating buttons. In Anki there are four, Again, Hard, Good and Easy; Scholarwire's review screen has two buttons, Didn't know it and Knew it, and a Too easy, show it less link under them. Under FSRS:
- Didn't know it means you did not remember the card. Stability drops and the card comes back soon, so you can relearn it before it fades further.
- Knew it means you remembered it. This is the normal answer and produces a normal increase in the gap.
- Too easy, show it less means no effort at all. The gap grows more than after "Knew it".
The one thing that hurts your schedule is rating generously: "Knew it" on something you did not know and only recognized once you saw the answer. FSRS trusts your rating to update its picture of how well you know the fact. A generous "Knew it" says your memory is stronger than it is, which pushes the next review out just when the card needed to come back sooner.
How should I use flashcards with FSRS?
A few habits follow from how the algorithm works:
- Rate honestly, every time. If you had to guess, it was not "Knew it".
- Review on the days cards are due, not in one weekly batch. A big batch works, but a smaller set each day spreads the recall out the way the algorithm intends and feels less exhausting.
- Keep the cards you keep forgetting. A card you mark "Didn't know it" repeatedly is telling you it is hard for you. It is the card most worth keeping, and often the one worth understanding more deeply rather than memorizing harder.
- Give new cards time. A new card has no history, so its first intervals are short whatever you do. It takes a handful of successful reviews before FSRS can space it out properly.
Spaced repetition assumes you have time to space things out. When you do not, the compressed version of the same idea is in how to study for an exam in five days, and getting review blocks onto a real week is how to turn Canvas assignments into a weekly study schedule. For how decks fit with the rest of the product, see how it works.