How to mark IGCSE Biology, Chemistry and Physics theory papers
IGCSE science theory papers are point-marked. Each marking point earns one mark if the student's answer contains the idea, uses the required key term correctly, and isn't contradicted elsewhere in the answer. The rules that catch teachers out are the list rule, contradictions, units in calculations and error carried forward (ecf). All are set out in the Science-Specific Marking Principles printed in Cambridge mark schemes.
How are the IGCSE science papers structured (2026–2028)?
Biology 0610, Chemistry 0620 and Physics 0625 share the same structure:
| Paper | Route | Type | Duration | Marks | Weighting |
|---|---|---|---|---|---|
| 1 | Core | Multiple choice (40 questions) | 45 min | 40 | 30% |
| 2 | Extended | Multiple choice (40 questions) | 45 min | 40 | 30% |
| 3 | Core | Theory | 1 h 15 min | 80 | 50% |
| 4 | Extended | Theory | 1 h 15 min | 80 | 50% |
| 5 | Both | Practical Test | 1 h 15 min | 40 | 20% |
| 6 | Both | Alternative to Practical | 1 h | 40 | 20% |
Core candidates (Papers 1, 3 and 5 or 6) can achieve grades C–G. Extended candidates (Papers 2, 4 and 5 or 6) can achieve A*–G.
Multiple choice marking is mechanical. The rest of this guide covers the theory papers (3 and 4) and Paper 6.
The six science marking rules you need to apply consistently
1. Key terms must be used correctly
A student who writes "the enzyme is killed" instead of "denatured" usually doesn't earn a mark that requires "denatured". Underlined words in the mark scheme, or a clear equivalent, must appear.
2. Spelling: close is fine, unless it becomes another word
Spelling doesn't need to be correct. But it must not turn one syllabus term into another: ethane/ethene, meiosis/mitosis, reflection/refraction. If you can't tell which term the student meant, don't award the mark.
3. The list rule
If the question asks for n answers, mark only the first n. Wrong answers count towards n; answers the scheme says to "ignore" don't. Students who write long lists hoping one is right lose marks this way, and the mark scheme intends that.
4. Contradictions cancel marks
If a student gives a correct statement and a contradictory incorrect one, don't choose the correct one. The mark isn't awarded. In Physics mark schemes this is flagged as CON.
5. Units and the final mark
In calculations, a missing or incorrect unit normally loses the final mark, not the method marks. Check whether the unit is already printed on the answer line. If it is, the student doesn't need to repeat it.
6. Error carried forward (ecf)
Where the scheme shows ecf, credit a correct method that uses the student's own wrong value from an earlier part. A wrong answer in 3(a) shouldn't cost every mark in 3(b) if the method in 3(b) is sound.
Subject-specific conventions
| Subject | Conventions to know |
|---|---|
| Biology 0610 | ; separates marking points. / gives alternatives. A = accept, R = reject, I = ignore. AVP = any valid point. ora = or reverse argument. AW = alternative wording. "max" limits marks from a list. |
| Chemistry 0620 | The June 2024 Paper 4 mark scheme has no abbreviation key. It uses numbered marking points (M1, M2), "ORA" and "not". Different terminology gets full credit if the meaning is the same. Equations: multiples of coefficients are acceptable, and state symbols are ignored unless asked for. |
| Physics 0625 | A, B, C and M marks. C is a compensatory mark: a correct final answer can compensate for missing method marks. owtte, ecf, cao, ORA, CON (contradiction) and insufficient. |
For a full glossary with worked examples, see IGCSE mark scheme abbreviations explained.
Worked example: an "explain" question (illustrative)
Question style: Explain why the rate of an enzyme-controlled reaction decreases above 40 °C. [3]
Mark scheme style:
- active site changes shape / enzyme denatured ;
- substrate no longer fits / fewer enzyme–substrate complexes ;
- fewer successful collisions ;
- R enzyme killed
| Student answer | Marks | Why |
|---|---|---|
| "The enzyme denatures, so the active site changes shape and the substrate can't fit. Fewer complexes form." | 3 | All three points. |
| "The enzyme is killed by the heat so it stops working." | 0 | "Killed" is rejected, and no other point is made. |
| "The active site changes shape so the substrate doesn't fit. The enzyme is also killed." | 2 | Two valid points. Whether "killed" alongside correct points counts as a contradiction depends on the scheme. Agree it at standardisation. |
The third row is exactly the kind of decision a department should agree before marking, not argue about afterwards.
Marking Paper 6: Alternative to Practical
Paper 6 assesses practical skills on paper: recording readings, drawing tables and graphs, identifying variables and suggesting improvements. Marking points here are often about form, not just content:
- Table headings with units, in the format the scheme expects.
- Readings recorded to a consistent and appropriate precision.
- Graphs with labelled axes, sensible scales, accurately plotted points and an appropriate best-fit line.
- Conclusions that refer to the data.
Graph and drawing marks depend on precise visual detail, so scan these pages flat and well lit.
Using AI to mark IGCSE science papers
Science theory papers are well suited to AI marking, because most marks are discrete points. What matters is whether the tool applies the science rules (list rule, contradictions, units and ecf) rather than just looking for keywords.
The Learning Mate marks handwritten science answers part by part against your mark scheme. It explains each mark and gives each student written feedback, and you can change any mark before you publish results.
FAQ
What is the list rule in IGCSE science mark schemes?
If a question asks for a set number of answers, only that many are marked, in order. Wrong answers count towards the limit, so extra answers after a wrong one aren't credited.
Does spelling matter in IGCSE science?
Not usually. Spelling doesn't need to be correct, but it must not be confused with another syllabus term, such as ethane and ethene.
Do students lose marks for missing units?
Usually they lose the final mark in a calculation if the unit is missing or wrong, unless the unit is printed on the answer line.
What is the difference between Paper 5 and Paper 6?
Paper 5 is a practical test in the lab (1 h 15 min). Paper 6 is a written Alternative to Practical paper (1 hour). Both are 40 marks and 20% of the qualification.
What grades can Core science candidates get?
Core candidates can achieve grades C to G in Cambridge IGCSE Biology, Chemistry and Physics.
Sources
- Cambridge IGCSE Biology 0610, Chemistry 0620 and Physics 0625 syllabuses 2026–2028, on each syllabus page at cambridgeinternational.org
- June 2024 Paper 41 mark schemes for 0610, 0620 and 0625, on each syllabus's past papers page at cambridgeinternational.org