Flashcards and Spaced Repetition: How to Use Them the Right Way
Reviewed by Prof. Dr. Alexander Holtermann · Updated 16 October 2026 · 6 min read
Write one question per card in your own words, answer before you flip, and review on a growing schedule: cards you know move back, cards you miss return soon.
Key takeaways
- Flashcards combine the two best-supported study techniques: retrieval practice (you answer from memory) and spaced practice (you review at increasing intervals).
- A good card asks one clear question and has one short answer. Long cards with lists of facts are the most common reason flashcards fail.
- Say or write your answer before you flip the card. Flipping and thinking “yes, I knew that” is recognition, not recall.
- Spaced repetition schedules cards by performance: easy cards come back after days or weeks, missed cards return within the same session or the next day.
- Paper boxes (the Leitner system) and flashcard apps both work. What matters is that you review a little almost every day instead of a lot right before the exam.
Why flashcards work (when used properly)
Flashcards are effective for one simple reason: they force you to retrieve information instead of looking at it. Retrieval strengthens memory more than restudying, an effect shown repeatedly since the classic experiments by Roediger and Karpicke (2006). In the review by Dunlosky et al. (2013), practice testing, which includes flashcards, was one of only two techniques rated “high utility”.
The second reason is spacing. A stack of cards can be reviewed across days and weeks, and the cards you struggle with can be shown more often. That combines retrieval practice with distributed practice, the other high-utility technique. Flashcards are therefore not a gimmick for vocabulary only; they are a general tool for anything that has to be recalled precisely: definitions, formulas, mechanisms, dates, cases, anatomical structures, key arguments.
What flashcards do not do well on their own: train long problem-solving or essay writing. For those, combine cards with practice problems and past exam questions.
How to write good flashcards
Most flashcard problems are card-writing problems. A card that asks “Explain the Krebs cycle” on the front and has 14 bullet points on the back cannot be answered reliably, so you end up skimming the back and calling it a day. Break big topics into many small, precise questions.
- One question, one answer: if the answer is a list, make one card per list item or a card for the number and the categories
- Use your own words, not copied sentences from the slides
- Ask questions, not just terms: “What does a p-value of 0.03 mean?” beats “p-value”
- Add a “why” or “how” card for important facts so you learn the connection, not just the label
- For formulas, put a short example problem on the front, not the formula name
- Use cloze cards (fill in the blank) for definitions with one key term
- Add a simple sketch when the content is visual, such as a graph or a structure
Spaced repetition and the Leitner system
Spaced repetition means reviewing each card at a growing interval that depends on how well you know it. The simplest version is the Leitner system, developed by the German science journalist Sebastian Leitner in the 1970s. You use several boxes. Every new card starts in box 1. If you answer a card correctly, it moves to the next box; if you miss it, it goes back to box 1. Each box is reviewed less often than the one before.
The principle behind it is well supported: spacing reviews out improves long-term retention, and the best gap grows with how long you need to remember (Cepeda et al., 2006). Flashcard apps automate the scheduling with an algorithm that estimates when you are about to forget each card and shows it just before that point.
| Box | Review every … | Card moves here when … |
|---|---|---|
| 1 | day | it is new or you missed it |
| 2 | 2 days | you answered it correctly from box 1 |
| 3 | 4 days | you answered it correctly from box 2 |
| 4 | 1 week | you answered it correctly from box 3 |
| 5 | 2–3 weeks | you answered it correctly from box 4 |
Paper or digital flashcards?
Both work. The best choice is the one you will use every day. Writing cards by hand forces you to condense, which is a learning step in itself. Digital cards are easier to carry, schedule and search, and they can contain images and formulas. Some students write cards by hand during the semester and use digital decks for review before finals.
| Paper cards | Flashcard app | |
|---|---|---|
| Writing | Slower, forces you to condense | Faster, risk of copying too much text |
| Scheduling | Manual (boxes) | Automatic, adapts to your answers |
| Portability | Bulky with many courses | Always on your phone |
| Distraction risk | Low | Higher (notifications, other apps) |
| Images and formulas | Hand-drawn | Easy to add |
A daily flashcard routine that fits into a semester
Short daily sessions beat long weekly ones. Ten to twenty minutes a day is enough for most courses if you start early. Add new cards on the day of the lecture, while the content is fresh, and review due cards every day. Before finals, the number of due cards will rise; that is normal and a sign that the system is working.
- Same day as the lecture: write 5 to 15 new cards on the key points
- Every day: review all due cards, saying the answer out loud or writing it down before flipping
- Be strict with yourself: a half-correct answer counts as missed
- Once a week: rewrite or split cards you keep missing; they are often badly phrased
- Two weeks before the exam: add cards from your practice-exam error log
Common flashcard mistakes
Flashcards can turn into busywork just like highlighting. These are the traps to avoid.
| Mistake | Better |
|---|---|
| Making hundreds of cards the week before the exam | Write cards continuously during the semester |
| Copying whole slides onto cards | One short question and answer per card, in your own words |
| Flipping before answering | Commit to an answer first, then check |
| Only learning one direction (term → definition) | Add reverse and example cards for key concepts |
| Skipping days and then facing 400 due cards | Review a little every day, even 10 minutes |
| Using only someone else’s premade deck | Edit or add cards so they match your course and wording |
Frequently asked questions
Are flashcards an effective way to study?
Yes, if you answer from memory before flipping and review on a spaced schedule. They combine retrieval practice and spaced practice, the two techniques rated most effective by Dunlosky et al. (2013).
How many flashcards should I review per day?
Review whatever is due, which for most students is 50 to 200 cards, or 10 to 30 minutes. Add 10 to 20 new cards per day per course during busy periods.
What is the Leitner system?
A paper-based spaced repetition method with several boxes. Correct cards move to a box reviewed less often; missed cards go back to the first box, which you review daily.
Should I make my own flashcards or use premade decks?
Making your own is better for learning because writing the card is already processing. Premade decks can save time, but adapt them to your course content and wording.
Do flashcards work for subjects like math or physics?
For definitions, theorems, formulas and when to use which method, yes. For problem-solving skills, combine cards with mixed practice problems and past exams.
Which flashcard app is best: Anki, Quizlet or RemNote?
Anki offers the most configurable spaced repetition, Quizlet the easiest sharing and study games, RemNote combines notes and cards. Our comparison article explains which fits which student; the best app is the one you use daily.
Sources and further reading
- Dunlosky, J., Rawson, K. A., Marsh, E. J., Nathan, M. J., & Willingham, D. T. (2013). Improving students’ learning with effective learning techniques: Promising directions from cognitive and educational psychology. Psychological Science in the Public Interest, 14(1), 4–58.
- Roediger, H. L., & Karpicke, J. D. (2006). Test-enhanced learning: Taking memory tests improves long-term retention. Psychological Science, 17(3), 249–255.
- Cepeda, N. J., Pashler, H., Vul, E., Wixted, J. T., & Rohrer, D. (2006). Distributed practice in verbal recall tasks: A review and quantitative synthesis. Psychological Bulletin, 132(3), 354–380.
- Brown, P. C., Roediger, H. L., & McDaniel, M. A. (2014). Make It Stick: The Science of Successful Learning. Belknap Press of Harvard University Press.
Your university’s examination regulations and style guide always take precedence.
Related articles
- Study techniquesPractice testing and spaced practice work best; interleaving, elaboration and self-explanation help; highlighting and rereading do little on their own.
- How to study for examsStart four weeks out: map what is tested, quiz yourself rather than reread, take past papers under timed conditions, and use the final week to review and sleep.
- Study scheduleA good study schedule starts from your fixed commitments, splits topics into short blocks, spaces reviews over days and keeps 20 % of the time as a buffer.
- Note-takingTake notes in your own words rather than verbatim, use a structure like the Cornell method and review them within a day by testing yourself, on paper or laptop.
- Flashcard apps comparedAnki has the strongest spaced repetition, Quizlet the easiest sharing and games, RemNote combines notes and cards. Pick the app you will open every day.
