Active recall: how to test yourself and check what you remember

A formula can look familiar on the page and still disappear when you need it in a test. Active recall gives you a way to check that gap: put your notes away and retrieve the answer yourself. You might explain an idea aloud, sketch a diagram or solve a short problem. Then compare your response with a reliable answer. That comparison tells you what to practise next.

Why should I test myself when I could read the notes again?

Roediger and Karpicke's 2006 experiments examined learning from texts. Taking recall tests improved retention on delayed assessments compared with additional studying. Dunlosky and colleagues also rated practice testing as a high-utility learning technique in their 2013 review. These findings support making retrieval part of your study routine. They don't promise a particular grade or show that recalling a formula is enough to solve every problem.

Reading still has a job: it helps you meet a new idea and understand explanations. Once you understand a short section, close it and try to explain it. If you cannot get started, return to a smaller piece of the lesson. Work through an example, then try a simpler question without looking. You don't need to stare at an empty page for ages.

What would active recall look like in a geometry lesson?

Use this short lesson on the Pythagorean theorem: in a right triangle ABC with the right angle at A, BC is the hypotenuse. It is opposite the right angle and is the longest side. The theorem states that BC² = AB² + AC². To find a side length from its square, take the positive square root. Express all lengths in the same unit before calculating.

Read the lesson, cover it and draw the triangle yourself. Mark the right angle. Then answer the questions below on paper. If you make flashcards, put each question on the front and its answer on the back. Keep the answer hidden until you have made an attempt.

• When can you use the Pythagorean theorem? Expected answer: when the triangle is right-angled.
• Which side is the hypotenuse when the right angle is at A? Expected answer: BC, because it is opposite that angle.
• What equation links the side lengths? Expected answer: BC² = AB² + AC².
• If AB = 9 cm and AC = 12 cm, what is BC? Expected answer: BC² = 81 + 144 = 225, so BC = 15 cm.

For the calculation, show the equation and the square root. A final answer of 15 on its own doesn't show whether you selected the right method. Include the unit in your final sentence: BC is 15 cm long. Check that this result is longer than either leg of the triangle.

How do I correct a wrong answer so I can use the correction?

Suppose you wrote BC = 9 + 12 = 21 cm. Name the mistake: you added the lengths directly, although the theorem adds their squares. Write BC² = 9² + 12² = 225, then BC = 15 cm. Cover the solution and try a different right triangle with legs of 7 cm and 24 cm. The hypotenuse should be 25 cm.

Mark each response as correct without help, incomplete or incorrect. For an incomplete answer, say what is missing. You may have remembered the equation but forgotten the condition that the triangle must be right-angled. Bring that question back in a later session. Getting an answer wrong gives you something to address; follow it with an explanation and another attempt.

How can I fit this into a twenty-minute session?

Try five minutes understanding a short section, seven answering questions with the notes closed, five checking your work and three retrying a difficult question. These timings are a practical starting point. Change them when a topic needs more explanation. At the beginning of your next session, answer a few earlier questions before you open the notes.

Vary the task once you know an answer. Rotate the triangle, change the numbers or ask why the method applies. For a definition, give an example as well as the wording. This checks whether you can use the idea when the question looks different. If the same concept keeps blocking you, ask your teacher for an explanation before creating more cards.

Which habits make active recall less useful?

• Flipping a card immediately: say or write an answer first so you can check what you retrieved yourself.
• Using vague prompts such as “Pythagoras?”: ask for a condition, an equation or a particular calculation.
• Accepting an answer because it sounds familiar: compare it with the specific points required.
• Studying only formula cards: include problems where you must choose a method and carry out the calculation.

You can use Graduo flashcards to ask yourself questions about your course. Check their answers against your notes, attempt each question before revealing the answer and decide when you will revisit the difficult cards. Make flashcards