How to make good flashcards, with rules backed by research

Why flashcards work (when they do)

Flashcards combine the two techniques with the best evidence in learning research: practice testing and spaced practice. Dunlosky and colleagues (2013) rated both as high utility after reviewing ten common study techniques. A card that makes you pull an answer out of memory is a small test; a deck you return to over several days is spaced practice.

The catch is that flashcards can also be used in ways that switch both off: cards you only glance at, and decks crammed in one sitting. Survey research shows how common that is. Wissman, Rawson and Pyc (2012) asked 374 undergraduates how they used flashcards and found that students understood the value of practising until they got cards right, but did not usually space their practice out or understand the benefit of doing so.

Rules for writing good flashcards

1. One idea per card. A card with five facts on the back is a paragraph, not a question. You will "sort of" get it right every time and never know what you're missing. Split it.
2. Make the front a real question. "Mitochondria" is a topic. "Where in the cell is most ATP made, and by what process?" is a question.
3. Ask for recall, not recognition. Larsen, Butler and Roediger (2008) note that tests requiring effortful recall, such as short answers, help retention more than recognition tests. If you can answer by recognising the word on the front, the card is too easy.
4. Mix in "why" and "how" cards. Definitions are the easy part. Exams also ask you to explain and apply.
5. Use your course's wording. Write the answer the way your lecturer or textbook does, so the card matches what the exam will expect.

Rules for using them

1. Say the answer before you flip. Out loud or in writing. "I knew that" after flipping doesn't count.
2. Use one big deck, not lots of little piles. Kornell (2009) found that studying one large stack beat studying the same cards in four smaller stacks, because the large stack spreads each card's repetitions further apart. Spacing beat cramming for 90% of the participants, yet after the first session 72% believed the opposite.
3. Don't drop cards too early. Kornell and Bjork (2008) found that letting students set aside cards they thought they knew had small but consistently negative effects on learning. Keep "known" cards in rotation, just less often.
4. Come back over days, not hours. A deck reviewed on four different days beats the same time spent in one evening. Our spaced repetition schedule sets out the gaps.

The most common flashcard mistakes

• Making cards the night before. All the effort goes into making them, with no time to space the reviews.
• Reading both sides together. That's rereading in a different format.
• Only definitions. Good for vocabulary, weak for understanding.
• Huge cards. Lists of seven items on one card. Turn them into an "order the steps" exercise or several cards.
• Never checking the source. A wrong card learned well is a wrong answer in the exam. This matters most with AI-made cards; see AI flashcards vs making your own.

Before and after: rewriting weak cards

• Before: "Osmosis" / "Movement of water across a partially permeable membrane from high to low water potential."
  After: "A red blood cell is placed in pure water. What happens and why?"
• Before: "Causes of WW1" / a list of four causes.
  After: four cards, one per cause, each asking how it contributed, plus one asking which your course treats as most important and why.
• Before: "Ohm's law" / "V = IR".
  After: "If resistance doubles and voltage stays the same, what happens to current?"

If writing the cards is what stops you starting, practice questions can do the same job. Ace turns your own slides, PDFs and notes into questions (multiple choice, type-the-answer, put-the-steps-in-order and others, depending on the material), checks every answer against your file, and shows the sentence that backs it. Our PDF to flashcards page shows the idea.

Frequently asked questions

Sources

1. Dunlosky, J., Rawson, K. A., Marsh, E. J., Nathan, M. J., & Willingham, D. T. (2013). Improving students' learning with effective learning techniques. Psychological Science in the Public Interest, 14(1), 4–58.
2. Wissman, K. T., Rawson, K. A., & Pyc, M. A. (2012). How and when do students use flashcards? Memory, 20(6), 568–579.
3. Larsen, D. P., Butler, A. C., & Roediger, H. L. (2008). Test-enhanced learning in medical education. Medical Education, 42(10), 959–966.
4. Kornell, N. (2009). Optimising learning using flashcards: Spacing is more effective than cramming. Applied Cognitive Psychology, 23(9), 1297–1317.
5. Kornell, N., & Bjork, R. A. (2008). Optimising self-regulated study: The benefits—and costs—of dropping flashcards. Memory, 16(2), 125–136.