Make an error notebook that helps you fix repeated exam mistakes

Field	What to write
Topic and question	Enough detail to find it again
My first wrong step	The exact line or choice that failed
Error type	Concept, calculation, reading, recall or time decision
Correct rule	One sentence that changes the method
Retry prompt	A question to solve with the solution closed
Review result	Independent answer, guess or still unclear

Use paper or your revision notebook. Keep the note short enough to reread before practice. If you need the whole solution, link to the question rather than copying every line.

Question: A price rises 20% and then falls 20%. What is the net change?

My wrong step: I cancelled the two percentages and answered zero.

Error type: Concept.

Correct rule: Each percentage uses the quantity immediately before that change.

Correct working: Start at 100. After the rise it is 120. After the fall it is 96. The net change is a 4% fall.

Retry prompt: Try a 10% rise followed by a 10% fall. Starting at 100 gives 110 and then 99: a 1% fall.

This entry points to the changed base, not just the final answer. Revisit percentage if you cannot explain that step.

A concept gap needs a lesson and a fresh example. A calculation error needs the exact calculation repeated carefully. A reading error needs the condition you overlooked written clearly.

For recall errors, turn the fact or formula into a closed-book prompt. For time decisions, record when you should have moved on. The same “practise more” advice does not fix every error.

Example: if a speed question uses metres while time is in hours, write “convert units before comparing rates”. Then solve a question with different units. That is more useful than writing “silly mistake”.

Before investing more time, ask: “Do I know a valid first step?” If not, mark the question and move on when the interface allows it. Return after securing questions you can solve.

If the method is clear but the calculation is long, compare the remaining time with the rest of the section. Use your own practice timing to set checkpoints. A single seconds-per-question rule does not fit every exam or question.

For a scoring scheme with reward $R$, penalty $P$ and probability $p$ of being correct, the expected score is $pR - (1-p)P$. It becomes positive when $p > P ÷ (R+P)$.

For an illustrative reward of 2 and penalty of 0.5, the threshold is 0.2. This mathematical threshold is not a blanket guessing recommendation: your probability estimate can be wrong, time has a cost, and your exam may use different rules. Confirm its marking scheme first.

After recording an error, try a similar question. Return later to the original question with its solution hidden.

If you solve it only because you remember the option, change the numbers or explain every step. For grammar, make another sentence. For reasoning, rebuild the diagram from the clues.

Keep repeated errors in the next review group. Move a repaired error to a longer interval once you can explain and apply the rule independently. Use the revision planner and revision method for reminders.