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After every test, mock or past paper: log each lost mark, give it an error type, and write the check that would have caught it. Once a week, drill the biggest bucket. Most students find that two or three error types cost them most of their marks.

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The four checks that catch most errors

• [ ] Plug back. Put your answer back into the original equation or context. Does it work? Does it make sense?
• [ ] Expand back. After factorising, multiply out and compare the middle term (20 seconds).
• [ ] Units ladder. Carry units through every line. Never cancel before you take a magnitude.
• [ ] Re-read the command term. State, describe, explain, evaluate? Does the answer do exactly that?

Error types (use these in the log)

• Method choice — started calculating before writing down what is given and what is asked
• Sign & arithmetic — (−1)(−4), 4², rounding too early
• Didn't check — a plug-back would have caught it
• Command term missed — described when asked to explain, listed differences for “compare”
• Definition gap — gave an example instead of a definition
• Units — missing or wrong units, unit conversion
• Misread question — answered a different question
• Format ignored — wrong form, no working shown, no diagram
• Time — ran out of time / spent too long

Guide: Five reasons you're not getting better at IB

Mistakes