How do examiners actually mark exam papers?
Through a structured process designed to produce consistency across many markers, which is a harder problem than marking accuracy itself.
The mark scheme. Written alongside the paper, it specifies acceptable answers, how marks are allocated, and — critically — what credit is given for method where an answer is wrong. This is why showing working matters: marks are frequently awarded for a correct approach even with an arithmetic error.
For extended writing, mark schemes use level descriptors rather than point-by-point marking. An examiner places a response in a band by matching it against descriptions, then decides where within the band it sits. This is why an essay is not marked by counting facts.
Standardisation. Before marking begins, examiners mark the same sample scripts and compare against the principal examiner's decisions. Those who do not align are not permitted to proceed. This is the main mechanism for consistency.
Mark scheme revision. The scheme is adjusted after seeing real responses — candidates produce valid answers nobody anticipated, and legitimate alternatives must be credited.
On-screen marking and item-level allocation. Most major exams are now scanned, and examiners mark individual questions across many scripts rather than whole papers. This improves consistency, since an examiner marking question 4 repeatedly develops a reliable standard for it, and prevents impressions from earlier questions influencing later ones.
Seeding and monitoring. Pre-marked scripts are inserted into examiners' allocations without their knowledge to check ongoing accuracy, and supervisors sample live marking.
Anonymity. Examiners see candidate numbers, not names or schools.
What this means for candidates:
Answer the question asked, since marks attach to the scheme's requirements.
Show working — method marks are free marks otherwise lost.
Use the mark allocation as a guide to length and depth.
Legibility matters, since an examiner cannot credit what cannot be read.
Past papers with published mark schemes are the most useful revision resource.