Spaced Repetition for Quranic Arabic: Why Flashcards Finally Stick

Almost everyone who has tried to learn Quranic vocabulary knows this feeling. You learn twenty words on Monday, and by Friday you remember four. The problem is not your memory. It is the way the words were reviewed, or rather, not reviewed.

Spaced repetition is a simple idea with a very large effect: review each word right before you would forget it, and wait a little longer every time. Here is how it works and how to use it for the Quran.

The forgetting curve

In the 1880s the psychologist Hermann Ebbinghaus measured how quickly he forgot lists he had memorized. The result, now called the forgetting curve, is steep: most new information fades within days. Just as important, he found that every well-timed review flattens the curve, so the memory lasts longer each time.

The dashed line is a word you studied once. The green line is the same word reviewed on day 1, 3, 7, and 15. Each review resets your memory to full strength, and each time the curve falls more slowly. After four short reviews the word is still there a month later.

How spaced repetition works

A spaced repetition system shows you a card, you try to recall the answer, and then you tell it how it went. If you remembered easily, the next review is pushed far into the future. If you forgot, the card comes back soon. Over time each word settles at its own rhythm.

The result is that your daily reviews stay manageable even as your vocabulary grows into the thousands. Words you know well cost you a few seconds every few months.

FSRS: a smarter scheduler

Older schedulers, like the SM-2 algorithm behind classic Anki, use fixed rules: multiply the interval by a number and adjust it a little each time. FSRS (Free Spaced Repetition Scheduler) is a newer, open-source algorithm that models two things for each card: how stable the memory is, and how difficult the card is for you. It then predicts the day your chance of remembering drops to a target, usually 90%, and schedules the review for then.

In practice, FSRS usually gets the same retention with fewer reviews. Anki adopted it as an option in 2023, and it is the scheduler Quranki uses for both vocabulary and memorization.

How to grade yourself honestly

Most apps give you four buttons. Using them honestly is what makes the schedule accurate:

• Again: you did not remember, or you got it wrong. The card comes back soon.
• Hard: you remembered, but it took real effort.
• Good: you remembered after a normal moment of thought. This should be your most common answer.
• Easy: instant and effortless. Use it sparingly.

Anki decks vs. a dedicated Quran app

Anki is a superb tool and many students of the Quran have used it for years. If you go that route, look for a deck that is ordered by Quranic frequency, includes the Arabic with full harakat, and shows each word in an ayah. Shared decks vary a lot in quality.

A dedicated Quran app can do a few things a general flashcard tool cannot:

• Connect every word to the text. When you learn رَحْمَة (mercy), you see the ayahs it appears in, with audio.
• Track coverage. You can see what share of each surah you now understand.
• Change the reader as you learn. In Quranki, once you master a word, its translation is hidden in the word-by-word reader, so reading becomes a live test.

Building the daily habit

1. Reviews first, new words second. Clearing due reviews keeps the schedule healthy.
2. Five to ten new words a day. See how pace affects your timeline.
3. Same time every day. After a prayer is an easy anchor.
4. Never skip reviews for a week. If life gets busy, pause new words instead.

The same principle works for memorizing the Quran itself. We explain how in how to memorize the Quran without forgetting.

Frequently asked questions