Active recall: how to study by testing yourself (five ways to do it tonight, and how to grade yourself honestly)

Active recall is studying by retrieving: you close the notes and produce the answer, the definition, the diagram or the solution from memory, then check it. It beats rereading because the effort of pulling something out of memory strengthens it, while reading it again only makes it familiar. In the best-known study, students who recalled a passage remembered more a week later than students who reread it four times. Here are five ways to do it tonight, and a way to mark yourself that does not lie to you.

What active recall is, in one paragraph

Active recall has two halves, in a fixed order. First you retrieve: with the notes closed, you write or say the answer. Then you check: you open the notes and compare. The order is the method. If you look first and nod along, you are recognising, not recalling, and recognition is cheap. You can recognise a face you could not describe. You can recognise a formula you could not write. The research calls the same thing retrieval practice, or practice testing, and it is ranked first in the evidence among the ten common study methods. Every form of it below has the same shape: produce, then check.

Why it works better than rereading (the studies)

The standard experiment is Roediger and Karpicke (2006). Students read a short passage. One group read it again. The other group wrote down what they remembered of it, with the passage closed. Tested five minutes later, the rereaders did slightly better. Tested a week later, the order reversed: the group that had recalled remembered about 56 per cent of the ideas, and the group that reread remembered about 42 per cent. In the second experiment the gap held against students who had read the passage four times. And the rereaders had been the more confident ones. Asked to predict how much they would remember, the students who only read the passage predicted more and recalled less (Roediger and Karpicke 2006). That is the trap. Rereading feels like learning because the words become familiar. Familiarity does not survive a question asked a week later.

The result is not a one-off. Karpicke and Blunt (2011) had students study a science text either by recalling it or by drawing a concept map while reading, which is an "active" method most teachers approve of. A week later the recall group did better, including on questions that asked them to draw a concept map (Karpicke and Blunt 2011). Rowland (2014) pooled dozens of experiments that compared a test with a restudy and found the testing advantage across them, larger when the test required recall rather than recognition (Rowland 2014). The review that rated ten study methods gave practice testing its highest rating (Dunlosky et al. 2013).

Why it works is less settled than that it works. The usual framing is Bjork's "desirable difficulties": the effort of retrieving a memory strengthens the route to it, so a harder, slower retrieval today leaves an easier one next week (Bjork 1994). Treat that as the picture, not the proof. The proof is the week-later test, and it has come out the same way for twenty years.

Five ways to do it tonight

Each of these is active recall. Pick by the material, not by mood.

1. Blurting (the blurting method). Take a blank page. Write the topic at the top: "enzymes", "the chain rule", "causes of the 1837 rebellions". Set a timer for five minutes. Write everything you know, in any order, in your own words, diagrams included. Stop when the timer stops. Open the notes and add what you missed in a different colour. The second colour is tonight's study list, and the page is a record of what you knew before you looked. Ten minutes a topic.
2. Cover-and-answer flashcards. A question on the front, the answer on the back, and nothing on the front that gives the back away. Say or write the answer before you flip. A card that reads "mitochondria" on the front is a label, not a question. "What does the mitochondrion make, and from what?" is a question. There is a whole guide on how to write a card that forces recall. A few seconds to a minute a card.
3. Redo a solved problem cold. Take a worked example from class or the textbook. Cover the solution. Redo it from the question on a blank page. Uncover and mark it line by line, not just the final answer. This is the maths and physics form of recall, and the guide on how to redo a solved problem cold has the marking rule. Five to fifteen minutes a problem.
4. Redraw the diagram. The Krebs cycle, a free-body diagram, the graph of a rational function with its asymptotes. Blank page, draw it from memory, label everything, then compare with the source and circle every wrong or missing label. How to redraw the diagram so that the labels do the testing is its own short guide. Five minutes a diagram.
5. Teach it to the wall. Explain the idea aloud, with no notes, to a wall, a pet or a patient friend. Say it as if the listener has never heard it. Then open the notes and find what you skipped or fudged. The structured version of this is the Feynman technique, and the guide on how to teach it out loud gives its four steps. Ten minutes an idea.

Four of the five need nothing but paper. That is the point. If you find yourself setting up a system for twenty minutes, you are not recalling yet.

How to grade yourself honestly

Recall only works if the check is honest, and the check is where most students cheat without meaning to. Use three marks, and write them down.

Mark	What happened	What it means for next time
Right	The answer came, complete, without a pause you noticed	Review it later, on a longer gap
Struggled	You got there, but slowly, or in parts, or you were not sure until you checked	Review it sooner
Wrong or looked	Anything else: a wrong answer, a half answer, or you peeked "to refresh"	Tonight's list; recall it again before you sleep

Two rules make the marks worth keeping. First, "I basically knew it" is Wrong. If you could not produce it, you did not have it. The feeling that you nearly had it is recognition, and recognition is what the exam will not test. Second, the attempt comes before the answer, always. The moment you glance at the answer first, that card has become rereading for the day, and you should mark it Looked, not Right. Chapter 1 of the free playbook is this rule on one page, because it is the rule that makes every other method work.

Keep a tally per idea, not per session. A small table — idea, date, mark — is enough. The next session's list is every idea whose last mark was Struggled or Wrong. That list is what turns one evening of recall into a plan.

Worked example: blurting a biology unit, then recalling the pathway

Say you are in SBI4U and the two ideas on this week's list are enzymes, active sites and the induced-fit model, and enzyme inhibition and feedback regulation. Here is what the method looks like on the page.

The blurt. Topic at the top: "Enzymes." Five minutes. What comes out, in the first colour:

• Enzymes are proteins. They speed up reactions by lowering the activation energy.
• The substrate binds at the active site. The enzyme is not used up.
• Induced fit: the active site changes shape slightly when the substrate binds, so the fit tightens.
• Heat or the wrong pH denatures the enzyme. The shape changes and the active site stops working.
• Each enzyme is specific to its substrate.

The timer stops. Open the notes. What was missed, in the second colour:

• Competitive inhibitors bind the active site and compete with the substrate for it.
• Non-competitive inhibitors bind somewhere else, an allosteric site, and change the enzyme's shape.
• Feedback inhibition: the end product of a pathway inhibits an enzyme early in the pathway, so the cell stops making what it already has enough of.

The second colour says exactly what tonight is about: inhibition, not the basics. So the recall question for the end of the session is written on inhibition:

"A competitive inhibitor is added to a reaction. What happens to the rate at a low substrate concentration? What happens if you then raise the substrate concentration a lot?"

Answer from memory, then check. The checkable answer: at a low substrate concentration the rate falls, because inhibitor molecules win some of the active sites. Raise the substrate concentration a lot and the rate climbs back toward the uninhibited maximum, because substrate molecules now outnumber the inhibitor at the active sites. The contrast is the second half of the answer: a non-competitive inhibitor's effect is not undone by more substrate, because it was never competing for the active site in the first place.

Mark it on the three-level scale. If you wrote "the rate goes down" and stopped, that is Struggled at best, because the question had two parts. Tomorrow's first card is "Why does extra substrate undo a competitive inhibitor but not a non-competitive one?"

Spacing: when to recall it again

One recall is a start, not a result. The second recall, two or three days later, is where the memory starts to hold, and a third about a week after that is what carries it to the exam. The guide on spacing says when to recall it again and how to run the dates on paper. The short version: tonight's Wrong is tomorrow's first card; tonight's Right comes back in three days; a card that is Right twice in a row waits a week.

The mistakes

• Reading the answer first "to refresh". This is the big one. It turns a recall into a reread, and it feels productive while it does it.
• Flashcards with the answer in the question. "Define osmosis: the movement of water across a membrane…" on the front tests nothing. The front asks; the back answers.
• Recalling only what you already know. It feels good, and it is why students report hours of recall and no change in marks. The three-level tally fixes this: you review the Struggled and Wrong marks first.
• Stopping at one pass. One blurt tells you what you know tonight. It does not change what you will know on Friday.
• Treating a practice test as a score. A mark of 64 per cent tells you very little. The list of the questions you got wrong tells you everything. A practice test is a list of ideas to recall, and the exams section shows how to turn one into next week's study list.

Summary box

• Active recall is produce-then-check, with the notes closed for the first half.
• It beats rereading at a week's distance, and rereaders feel more confident while remembering less.
• Five ways: blurt a page, cover-and-answer cards, redo a solved problem cold, redraw the diagram, teach it to the wall.
• Mark yourself on three levels — Right, Struggled, Wrong or looked — and "basically knew it" is Wrong.
• Keep a tally per idea; the Struggled and Wrong marks are the next session's list.
• Recall each idea again in two or three days, and again in a week.