Spaced Repetition (SRS)
Studying more isn't studying better. Spaced repetition is the scientific technique that helps you remember more with less review time.
What is spaced repetition
Spaced repetition (SRS) is a memorization technique based on how the human brain learns and forgets. Instead of reviewing all content uniformly, you focus on the cards you haven't mastered yet and set aside those already fixed in memory.
The scientific basis comes from the forgetting curve, described by psychologist Hermann Ebbinghaus in the 19th century: without review, we forget most new information within hours or days. Spaced repetition interrupts this process by reviewing content at the right moment, before forgetting sets in.
The practical result: you learn faster, retain longer, and spend less time reviewing what you already know.
How Play Flashcards applies SRS
In Play Flashcards, each card accumulates three metrics across your study sessions:
- Accuracy rate: the percentage of times you answered correctly over time.
- Consecutive correct answers: how many times in a row you answered correctly without any mistake.
- Last study date: when the card was last studied.
These three metrics form a picture of your mastery of each card. When any one of them signals that the card needs attention, it becomes pending.
When a card becomes pending
A card is pending when the SRS identifies that it needs to be reviewed. This happens if any of the following conditions is true:
- The accuracy rate is below the configured minimum.
- The consecutive correct answers count is below the configured minimum.
- The card has not been studied for more days than the configured interval.
This criterion is intentional: a card you answer correctly often but haven't seen in weeks is still pending. Likewise, a card with a good historical rate that you missed in recent sessions becomes pending again immediately.
A mistake resets the sequence
A single mistake resets the consecutive correct answers to zero. This ensures you only truly master a card when you answer consistently, not by luck.
The parameters you control
Play Flashcards SRS has four configurable parameters in your profile, all with default values designed for most use cases:
| Parameter | Default | What it controls |
|---|---|---|
| Accuracy rate | 75% | Below this percentage, the card remains pending. |
| Consecutive correct answers | 5 | Minimum consecutive correct answers with no mistakes. |
| Study frequency | 7 days | Cards not studied within this period become pending again, even if already mastered. |
| Cards per session | 20 cards | Maximum number of cards per SRS study session. |
You can adjust these values to match your learning pace. Those who study daily can reduce the study frequency interval; those with a large deck can increase the cards per session limit.
What an SRS study session looks like
When you start an SRS session on a deck, Play Flashcards automatically selects the pending cards, shuffles them, and presents them one by one. For each card you see the front, decide your answer mentally, and reveal the back to check.
You then indicate whether you got it right or wrong. That answer is recorded immediately and updates the card's three metrics. At the end of the session, the system shows your result: how many cards you got right and how many you missed.
If there are no pending cards in the deck, the system lets you know that everything is up to date and there is nothing to review at the moment.