One fact per card means each flashcard tests exactly one piece of retrievable information. The front asks a specific question; the back gives a 1–5 word answer. This makes it possible to know immediately whether you got it right — which is what makes spaced repetition work.
Why One Fact Per Card
When a card has multiple facts, you can’t tell which one you remembered and which you guessed. You might recall one part perfectly and blank on another — and still move the card forward. Over time, half-known cards accumulate and the system stops working. See the Leitner System guide for how card quality affects the whole system.
Examples That Follow the Rule
- Q: What is the boiling point of water at sea level? / A: 100°C
- Q: Who wrote Hamlet? / A: Shakespeare
- Q: In Python, which function returns the length of a list? / A: len()
- Q: What does the Krebs cycle produce? (one answer) / A: ATP
Examples That Break the Rule
- Q: Tell me about the mitochondria. / A: [paragraph] — too vague, too long
- Q: What are the three branches of the US government? / A: Legislative, Executive, Judicial — this is a list: split into 3 cards
When One Fact Isn’t Enough
For concepts with a chain of reasoning (a proof, a process, a narrative), use a sequence of cards — one per step. Download the quality checklist to test every card before it enters Box 1.
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