TL;DR:
Active recall means pulling an answer out of memory instead of looking at it again.
Turn a page of notes into a mix of define, explain, compare and apply questions, then answer each one from memory before you check.
Mark misses, and ask the missed questions again later.
You have a clean page of chemistry notes on the mole. You read it twice on the bus and it all looked familiar. Then the first practice question asks how many molecules are in 36 g of water, and the page, which was so clear a moment ago, offers nothing.
Looking familiar and being retrievable are different things. Active recall is the habit of testing the second one. This guide takes that single page and turns it into 12 questions, then shows how to use them.
Why testing yourself is different from rereading
Rereading shows you the answer, so there is nothing for your memory to do. Trying to recall forces your memory to rebuild the answer, and the effort of rebuilding, including the times you fail, is what makes the answer easier to reach next time.
It also gives you honest information. A question you cannot answer is a clear signal of what to study, while a page you can read smoothly tells you nothing about what you could produce on an exam.
What you need
One page of notes you trust. Check it against the textbook first so you do not drill a mistake.
A blank sheet or a document for the questions, and a second one for answers you write from memory.
About twenty-five minutes for the first run on a page, and ten for later rounds.
Making the questions: four types
A page of only "What is X?" questions trains one kind of memory. Mix these four types, and aim for about three of each from a full page.
Define: what does this term mean, in your own words?
Explain: why does this happen, or how does this work?
Compare: how is this different from that thing it gets confused with?
Apply: use it on a new number or situation.
Worked example: one page of chemistry notes becoming 12 questions
The page covers the mole: Avogadro's number (6.022 × 10²³ per mole), molar mass in grams per mole, and using moles in reaction equations. Here are the 12 questions, with the answers hidden on your separate sheet.
# | Type | Question |
|---|---|---|
1 | Define | What is a mole? |
2 | Define | What is molar mass, and what are its units? |
3 | Define | What does the coefficient in a balanced equation tell you? |
4 | Explain | Why can you not count atoms directly, so chemists count in moles? |
5 | Explain | Why do 1 mol of carbon and 1 mol of oxygen atoms have different masses? |
6 | Explain | Why must an equation be balanced before you use mole ratios? |
7 | Compare | How is a mole of atoms different from a mole of molecules of the same element? |
8 | Compare | How are mass in grams and amount in moles related and different? |
9 | Apply | How many moles are in 44.01 g of CO₂ (M = 44.01 g/mol)? |
10 | Apply | What is the mass of 0.50 mol of NaCl (M = 58.44 g/mol)? |
11 | Apply | How many molecules are in 36 g of H₂O (M = 18.02 g/mol)? |
12 | Apply | In 2H₂ + O₂ → 2H₂O, how many moles of water form from 3.0 mol H₂? |
Checking the apply answers
Q9: 44.01 g ÷ 44.01 g/mol = 1.000 mol.
Q10: 0.50 mol × 58.44 g/mol = 29.22 g, so about 29 g.
Q11: 36 g ÷ 18.02 g/mol = 2.00 mol; then 2.00 × 6.022 × 10²³ = 1.20 × 10²⁴ molecules.
Q12: the ratio of H₂ to H₂O is 2 to 2, which is 1 to 1, so 3.0 mol of H₂ gives 3.0 mol of H₂O.
Q11 is the one that exposed the gap on the bus: it needs two steps, grams to moles and moles to molecules. Notice that it only appears if your question set includes an apply question, which is why the types matter.
How to run a round
Answer from memory: Cover your notes. Write or say each answer fully. A guess is fine; a peek is not.
Check and mark: Compare with the notes. Mark each question as right, partly right or missed, and write the correct answer for the last two.
Re-ask the misses: Ten minutes later or the next day, answer only the marked questions again. Retire a question after it is right two times in separate sessions.
Mistakes that weaken recall practice
Reading the question, then the answer, then thinking "I knew that". Commit to an answer before you look.
Only writing define questions. They are the easiest to ask and the least like most exam questions.
Never revisiting the misses. The point of marking is to ask them again.
Making questions from bad notes. If the page has an error, the questions will drill it.
Your plan for this week
Choose one page from your most recent class and write 8 to 12 questions in a mix of the four types.
Do a round today, re-ask the misses tomorrow, and a full round again at the end of the week.
Next page: write the questions during class in the margin, so you do not have to build them afterwards.
If you would rather be asked than write them, DuckyHelper can quiz you on a page you have open, out loud, when you ask for it. It is there from one key press; try it for 10 minutes with no card.
Frequently asked questions
How many questions per page is right?
Enough that each real idea is covered at least once. For most pages that is between 8 and 12.
Do I have to write the answers out?
Saying them aloud works too, but writing shows you exactly where your answer was thin when you check.
Get started
