What is active recall?

There is a quick test for any study session: is the answer coming out of your head, or going in through your eyes? Active recall is the first. Reading a summary, scrolling back through highlights and rewatching a video all put the material in front of you again, which is review. Recall starts once the material is out of sight and you have to produce it yourself.

• A blank page: write down everything you remember about a chapter, a talk or a post, then compare it with the source. Students often call this a brain dump.
• A question you answer before looking: on a flashcard, in a quiz, or one you wrote in the margin of a book.
• Explaining it to someone: telling a friend how an idea works, with no notes in your hand, is recall with an audience.
• Answering in your head: quick and silent, and still recall, as long as you settle on an answer before you check.

Flashcards are a tool, and they count only when you use them this way. Flipping a card after a glance, before you have formed an answer, turns it back into reading.

1. Choose the question: turn what you want to keep into a single question, such as "What should each line of a CV start with?" Add a why or how question for anything that has a reason behind it.
2. Put the source away: shut the book, close the tab or swipe the video off the screen. If the answer is still in view, your eyes will find it.
3. Answer in full: say it in your head, out loud or on paper. Aim for the whole answer, reason included, before you allow yourself a look.
4. Compare with the source: open it again and go through your answer line by line. Note what you left out as well as what you got wrong.
5. Grade yourself: decide whether you forgot it, half knew it or knew it fully. Be strict, because the grade decides when you try again.
6. Repair the gap: read only the part you missed, then close the source and recall that part once more.
7. Come back later: ask yourself the same question after a gap of days, and make the gap longer each time you get it right.

A good question has one clear answer that you could not guess from the question itself. Four habits help.

• One idea per question. "What did the video say about hooks?" is too broad to grade, while "Which hook holds back the method until later in the video?" has one answer.
• No yes or no. A question you can answer with a coin flip tests luck.
• Keep the answer's words out of it. When a question repeats half of its answer, you end up recognising the rest, which is easier than recalling it.
• Ask for the reason. "Why should only one thing change in an ad test?" makes you rebuild the idea, and "How many things should change?" only checks a number.

• Rereading and calling it revision. Each pass makes the text more familiar, and familiarity is easy to mistake for knowing. The feeling tends to vanish the moment you have to say it without the page.
• Highlighting as you go. Choosing a line to colour is a judgement made with the text in front of you. You finish with a colourful page and no attempt at recall behind it.
• Recognising instead of recalling. Picking from options, or nodding at the back of a flashcard, checks whether an answer looks right. Recall means producing it with nothing to choose from.
• Peeking early. A glance at the answer halfway through your attempt ends the attempt.
• Grading kindly. Counting a half answer as a full one sends the question further into the future than your memory can carry it.
• Doing it all in one sitting. Recalling the same item five times in a row feels productive, and the next section shows why spreading those attempts out does more.

Recall is about how you review, and spacing is about when. In a 2011 experiment by Jeffrey Karpicke and Althea Bauernschmidt, people studied a set of items until they could recall each one, then recalled them on three more tests laid out on different schedules. Putting long intervals between those tests improved long-term retention by 200% compared with giving the same three tests back to back.

The same study found no evidence that the shape of the schedule mattered on its own. Gaps that grew, stayed equal or shrank did about as well as each other; the total spacing made the difference. Growing gaps are still a practical choice, because they spend fewer reviews on what you already know well, but the lesson of the study is to spread the attempts out.

Recall also seems to make a memory sturdier under pressure. In a 2016 study in Science, Amy Smith, Victoria Floerke and Ayanna Thomas had people learn material either by restudying it or by taking practice tests. A day later, half of them were put under acute stress before a memory test. The restudy group showed the usual drop under stress, and the authors describe the group that had practised recall as immune to it.

scrollandlearn turns posts you save from 15+ platforms into lessons, and Today's quiz asks questions written from those lessons. On a day when lessons are due, it asks a few, and every one of them runs through the steps above.

• The question shows on its own. The lesson stays out of sight, so the answer has to come from you.
• You answer in your head. There is nothing to type and no options to pick from.
• Show answer reveals the answer, so you compare right after your attempt.
• You grade it Forgot, Kind of or Knew it. Under each button the app shows when that grade brings the lesson back, from Tomorrow after Forgot to months away for a lesson you keep knowing.
• If a question is not the one you would ask, Edit lesson lets you rewrite it.

The example is an illustration of the lesson a LinkedIn post about ad testing becomes. Its question, "How many things should change in one ad test, and why?", has two parts. Saying "one" and stopping there is half an answer and earns Kind of. Saying one, because a test only teaches you something when a single thing changes, is the whole answer. Say the full sentence to yourself before you tap Show answer, or jot it on paper if you want to be sure you committed to it.