Flashcard apps: how spaced repetition helps you remember more

Flashcards are a simple study tool, and apps have added scheduling that paper cards cannot do. Here is why flashcards work when they are used well, what spaced repetition adds, how the main apps differ, and how to make cards that actually help.

Why flashcards work

A flashcard is a small practice test. You see a question, try to recall the answer, then check. That act of pulling information out of memory is called retrieval practice. A 2013 review of learning techniques led by the psychologist John Dunlosky rated practice testing as high utility, alongside distributed practice, which means spreading study over time. Rereading and underlining, two common habits, were rated low.

The catch is that a flashcard only works if you genuinely try to recall the answer before you flip it. Cornell University’s Learning Strategies Center describes the effort of remembering as the point: the struggle is how the learning happens.

That effort can feel worse than it works. In a 2006 experiment by the psychologists Henry Roediger and Jeffrey Karpicke, students who read a passage again felt more confident than students who tested themselves on it, and did better on a test five minutes later. But on tests two days and a week later, the students who had tested themselves remembered substantially more.

What spaced repetition adds

Spaced practice is the opposite of cramming, and flashcard apps automate it. Instead of going through the whole deck every time, the app decides when each card comes back, so you spend more time on the material you find hard and less on what you already know. A 2006 review of 317 experiments on spacing, by Cepeda and colleagues, found that the best gap between study sessions grows with how long you need to remember the material.

The same trap shows up here. In a 2009 study by the psychologist Nate Kornell, students learned word pairs with flashcards either in one large stack, which spaces each card out, or in four smaller stacks studied one at a time. The single large stack worked better for 90% of the students, yet after the first session 72% of them believed the small stacks had worked better. Studying the night before the test lost to spacing too. If you use paper cards, keep the deck together rather than splitting it into small piles.

Anki is one example. After each card you rate how well you recalled it, and Anki schedules the next review for when you are most likely to forget. It also offers an alternative scheduler, the Free Spaced Repetition Scheduler (FSRS), which estimates more precisely how much you are likely to forget so you can remember more in the same amount of time. RemNote and Brainscape run on spaced repetition too. Brainscape asks you to judge your own confidence in each card, and uses that to decide how often to show it.

The main apps

Anki is free and open source on Windows, Mac and Linux, with a free sync service, AnkiWeb, to keep your cards in step across devices. AnkiDroid for Android is free; AnkiMobile, the official iPhone and iPad app, is paid, and its sales fund Anki’s development. Cards can hold audio, images, video and scientific notation, the app copes with decks of more than 100,000 cards, and you can change card layouts and review timing, install add-ons and use decks others have shared.

Quizlet holds millions of flashcard sets made by students and teachers, so for many courses someone has already made a set. It runs on the web and has official iOS and Android apps, with study modes that include Flashcards, Learn and Test.

RemNote combines note-taking and flashcards in one app, so you can turn your notes and PDFs into cards as you go. Its Exam Scheduler asks for your exam date and tells you what to study each day until then, and it works offline.

Brainscape is built around confidence ratings and spaced repetition, and can use AI to make cards from your own material. Its library mixes cards made by users with decks checked by experts and publishers.

Make your own cards

Ready-made decks are tempting, and for a standard vocabulary list they can save time. But Cornell’s center lists making flash cards as a preparation strategy and using them as a review strategy, and its advice is to make something new from your material rather than passively going over it again. Writing a card forces you to decide what matters and to put it in your own words, which is learning in itself. Several of these apps can now generate cards with AI; check every one against your notes, because a card that is wrong teaches you the wrong thing.

Keep each card to one question with one answer. Ask why and how, not just what. And add new cards as the course goes on rather than building a huge deck the week before the exam: spaced repetition needs time to space.

Fit cards into a wider plan

Flashcards suit facts, terms, formulas and definitions. For essays and problem sets, add practice exams and worked problems. Use them as one part of a study plan, a few minutes every day, and they will carry the details while you spend the rest of your time on understanding.