How to write good flashcards

A good flashcard asks one question with one answer you can give from memory. Rules from Wozniak and a worked example, from a textbook paragraph to cards.

5 min read

A good flashcard asks one question that has one answer, and you can give that answer from memory in a few seconds. Most flashcard decks that people abandon fail on that sentence: the question is vague, the answer is a paragraph, or the card holds five facts at once.

#The method in a few lines

• One idea per card.
• A question with a single right answer, not a topic.
• A fill-in-the-blank (cloze) for lists and definitions.
• A picture when the knowledge is visual.
• Your own words, with a clue that tells similar cards apart.
• Test each card by answering it cold. If you hesitate over what is being asked, rewrite it.

#Why it works

Reviewing a card is a recall test, and recall tests are what make memories last (see spaced repetition). A card is only a good test if it asks for one thing.

Piotr Wozniak, who built the SuperMemo software, collected his advice in twenty rules of formulating knowledge in 1999. The ones that matter most for beginners are:

• Do not learn if you do not understand. A fact you cannot place is hard to keep.
• Stick to the minimum information principle. Make each item as small as it can be.
• Cloze deletion hides part of a sentence. It is a fast way to make a card from a text.
• Use imagery. A picture can carry what words cannot.
• Avoid sets and enumerations. A card asking for a list of eight things gets a partial answer, and a partial answer gets one rating for eight facts.
• Combat interference. Cards that look alike get mixed up. Add what tells them apart.
• Optimize wording. Shorter and more precise is better.
• Personalize and provide examples. A fact linked to something you know sticks.
• Prioritize. You do not need a card for everything.

The practical reason behind the minimum information principle is the schedule. A card gets one rating. If it holds three facts and you know two, whichever rating you give is wrong for one of them.

#How to turn a text into cards

Take a sentence like this one, from a history lesson:

The Treaty of Versailles was signed on 28 June 1919 in the Hall of Mirrors of the Palace of Versailles, five years to the day after the assassination of Archduke Franz Ferdinand.

Compare this with the card many people write first: the front says "Treaty of Versailles" and the back copies the textbook paragraph. You read it, feel that you know it, and press a rating. The recall that makes memory last never happens.

#Lists

A list on one card is the usual trap. Turn it into a cloze with one number per item:

The planets nearest the Sun, in order: {{c1::Mercury}}, {{c2::Venus}}, {{c3::Earth}}, {{c4::Mars}}.

That makes four cards. Each one hides one planet and shows the others as context, so you can tell which one you know and which one you keep missing.

#Pictures

Anatomy, maps, circuit diagrams and charts are better learned from the picture itself. Hide the labels and ask for them one by one: this is called image occlusion. For short answers that need to be exact, such as a spelling, a formula or a command, make the card ask you to type the answer.

#Mistakes to avoid

• Copying the textbook. If you did not rewrite it, you probably did not process it.
• Yes or no questions. "Was Versailles signed in 1919?" can be answered by a guess. Ask for the date.
• Vague questions. "What do you know about Versailles?" has no end. If you cannot say when an answer is complete, the card is too open.
• Long answers. If the back needs more than a line or two, split the card.
• Making cards before you understand. You end up memorizing words you cannot use.
• Keeping cards you keep forgetting. A card that fails again and again is usually badly written, not hard. Rewrite it, split it, or add a clue.
• Cards for everything. Keep cards for what you need to recall without help. The rest belongs in notes.

#In Prior

Prior has five card types: Basic, Reversed (two cards, front to back and back to front), Cloze, Type the answer and Image occlusion. Card types shows each one.

• The […] button hides the selected words as a cloze deletion. If you type the {{c1::…}} form by hand, the card becomes a cloze card on its own.
• Fields are Markdown. You can highlight, color text, draw a small figure with an svg or mermaid code block, and add images.
• Stats lists your Leeches, the cards you keep forgetting. They are the first to rewrite. The card browser lets you search and edit your cards.
• Create from a course reads a PDF, pasted text or one of your notes and proposes cards. You keep, edit or drop each one before anything is added. See Write cards with AI. Prior AI is told to write one idea per card, avoid yes or no questions and use cloze for lists.
• With Claude Code you can have your own Claude write a deck through the make_flashcards prompt, which follows a longer version of these rules.

Read the cards the assistant proposes as you would read any card: if you could not answer it cold, change it. Decks and packs shows how to keep one pack per course with a subdeck per chapter.