What "allow", "accept", "do not accept" and "consequential error" mean — and how to use mark schemes to actually improve your answers.
Most students use mark schemes the wrong way. They check whether their answer matches the model answer, tick it or cross it, and move on. This wastes most of the value a mark scheme provides. This guide explains what every part of a mark scheme means and how to use them as a genuine revision tool rather than just a checking mechanism.
Mark schemes are published by AQA, Edexcel and OCR after each exam series and are freely available on their websites. They are structured documents with specific notation that has precise meaning. Understanding that notation is the first step.
A typical mark scheme entry for a short answer question looks something like this:
Question: Explain why increasing temperature increases the rate of reaction. [3 marks]
Award 1 mark each for any THREE of: particles have more kinetic energy (1); particles move faster (1); particles collide more frequently (1); a greater proportion of collisions exceed the activation energy (1); allow: more successful collisions per second (1); do not accept: particles have more energy (without specifying kinetic)
Let's break down exactly what each part means.
For short and medium-length questions, marks are awarded one per correct, distinct point. "Any THREE of" means the mark scheme lists more valid points than there are marks available — you only need to give three of them to score full marks. You don't need to give all possible points, just enough distinct ones.
"Distinct" is important. If two of your answers say essentially the same thing in different words, they count as one point, not two. "Particles move faster" and "particles have higher speed" are the same point — you would only get the mark once.
"Allow" and "accept" in mark schemes mean that alternative phrasings or slightly different answers are also worth the mark. This is significant because it shows the examiner is not looking for one specific wording — they are looking for evidence that you understand the concept.
"Allow: more successful collisions per second" tells you that if a student writes "there are more successful collisions each second", they score the mark even though the model answer uses different language. When you're revising with mark schemes, the "allow" entries show you the range of acceptable understanding, not just the most precise version.
"Do not accept" is the single most instructive part of any mark scheme for a student who wants to improve. It lists the specific wrong or insufficiently precise answers that students commonly write — answers that feel right but don't score.
"Do not accept: particles have more energy" is particularly revealing. Students constantly write this and it feels like a reasonable answer. But "energy" is too vague — the mark scheme requires "kinetic energy" specifically, because particles in a hotter substance have more kinetic energy but the total energy of the system hasn't necessarily changed. The specificity matters.
The "do not accept" list in a mark scheme is a direct record of the wrong answers that thousands of students have written before you. Reading it is the closest you can get to seeing the exact mistakes to avoid in your own answers.
Extended writing questions (usually 4, 5 or 6 marks) use a different structure. Instead of awarding one mark per point, the examiner reads the whole answer and places it in a level. A typical three-level mark scheme looks like:
The mark scheme then lists indicative content — the points that a full-marks answer would cover. These are not a checklist where you need every point to score full marks, but a guide to the kind of content expected at each level.
After writing a practice answer, read the level descriptors carefully and honestly decide which level your answer belongs in. Then read the indicative content and identify which points you missed. Write out what a Level 3 answer to that question would look like — not copying the mark scheme, but writing your own full answer using the indicative content as a guide. This is more useful than simply noting you scored Level 2.
In calculation questions, "consequential error" or "error carried forward (ecf)" marking means that if you make an error in an early part of the question and carry the wrong value through to subsequent parts, you can still score the method marks for those later parts — provided your working is consistent with your earlier value.
Example: if a question asks you to calculate concentration in part (a) and use it in part (b), and you get part (a) wrong but correctly substitute your wrong answer into the right formula for part (b), you score the marks for part (b) method. The mark scheme indicates this with "allow ecf from (a)".
The practical implication: always complete every part of a calculation question, even if you know an earlier part is wrong. You may still score significant marks.
The most effective way to use mark schemes is not to check answers after doing them passively, but as part of an active revision process:
AQA mark schemes are freely available at the AQA past papers and mark schemes page. Edexcel's are at the Edexcel past papers page.
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