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A student can know every fact on the specification and still lose marks in a GCSE science exam. Often the reason has nothing to do with content. It comes down to misreading a single word at the start of the question.
In short: GCSE science command words such as describe, explain, evaluate, and calculate each require a different type of answer. Describe asks for what happens, explain asks for why it happens, evaluate asks for a balanced judgement, and calculate asks for working shown to a numerical answer. Mixing these up is one of the most common reasons students lose easy marks.
Below, we explain what each command word actually requires, the mistakes examiners see most often, and where structured practice, including GCSE science tutoring, tends to close the gap fastest
Exam boards including AQA, Edexcel, and OCR publish mark schemes built around command words. Each word signals a specific type of thinking the examiner is checking for, not just a general instruction to ‘write about’ the topic. A student who answers an explain question with only a description has technically answered a different question to the one that was asked, and the mark scheme will not reward it.
This is not a knowledge problem. It is a translation problem, between what the question is asking and what the student writes down. That distinction matters because it means the fix is about exam technique, not re-learning content from scratch.
These two words are responsible for more lost marks than any other pair on the GCSE science papers, because they often appear back to back in the same question.
Describe means stating what is observed or what happens, in the correct order, using data or observations from the question. A describe answer for a graph might state that the rate of reaction decreases as the reactants are used up, without saying why.
Explain means giving the scientific reason behind that pattern. An explain answer for the same graph would add that the rate decreases because there are fewer reactant particles, so collisions between particles become less frequent.
A useful habit for students is to check whether their answer contains the word ‘because’. A describe answer usually should not need one. An explain answer almost always should.
Evaluate questions ask students to weigh up evidence, methods, or conclusions, and reach a justified judgement. These are often worth the most marks on a paper and are marked using levels, meaning the overall quality and structure of the answer matters as much as individual facts.
Students who only list advantages, or only list disadvantages, typically lose marks even if every individual point is scientifically correct, because the mark scheme is checking for balanced reasoning, not just knowledge.
Calculate questions test maths skills in GCSE science directly, and they follow a mark scheme that rewards method as much as the final answer. A typical mark scheme awards separate marks for selecting the correct equation, substituting the right values, and stating the answer with the correct unit and appropriate significant figures.
This means a student who makes an arithmetic slip but shows correct working can still pick up two out of three marks, while a student who writes only a wrong final answer, with no working shown, often receives zero. Practising the underlying maths, rearranging equations, converting units, and working with standard form, tends to matter as much as knowing which equation to use in the first place.
Command word mistakes are usually easy to spot once someone reviews a student’s exam answers directly, but hard for a student to catch in their own work. This is where GCSE science tutoring UK tends to make the fastest difference, because a tutor can mark practice answers against the actual exam board mark scheme and show a student exactly where a describe answer drifted into explain territory, or where a calculate answer lost marks for missing working.
GCSE science online tuition UK makes this kind of focused, mark-scheme-based feedback accessible on a flexible schedule, which matters for students juggling several subjects in the run-up to exams. Whether a student is looking for GCSE science tutoring UK-wide or a specific online tutor for one exam board, the most useful sessions tend to focus on past-paper technique, not just content revision.
Describe asks what happens, using observations or data, with no reasons required. Explain asks why it happens, using a scientific concept to justify the pattern described.
This varies by exam board and paper, but evaluate questions are typically worth more marks than describe or state questions, since they are marked using levels that assess the structure and balance of the whole answer, not single facts.
Most mark schemes award method marks for correct working even if the final answer is wrong, which is why examiners consistently advise showing every step rather than writing only a final number.
Yes. GCSE science online tuition sessions can be structured entirely around past-paper technique and command words, using real mark schemes to show a student exactly where marks are being lost.
Most students lose marks on command words for the same handful of reasons, and those reasons are straightforward to fix once someone points them out. If a student would benefit from working through this with a tutor who marks against the real exam board scheme, book a free consultation to find the right support ahead of exam season.
GCSE Sciences can assist you in advancing your academic knowledge and increasing your understanding of core concepts through our practical approach based courses.
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