What do B, M, C and A mean in OCR A Physics mark schemes?

B marks are independent points, M marks are method marks, C marks are compensatory method marks that can be implied by later working, and A marks are accuracy or answer marks.

Can I still get marks if my final numerical answer is wrong?

Yes. OCR mark schemes can award method marks and sometimes error-carried-forward credit when later working follows correctly from an earlier arithmetic, transcription or power of ten error.

Why can a response that looks correct lose a mark?

A specific B mark may be missing, a required M mark may not be shown, the answer may contain a contradiction, or the method may use wrong physics even if the final number looks plausible.

OCR A Level Physics H556 | Exam technique

Understanding OCR A Physics mark schemes

A mark scheme is not just a list of answers. It is a set of rules for deciding exactly which pieces of physics, method and accuracy have been shown. Once you can read those rules, your revision becomes much sharper.

01 Why this matters

Marks are awarded for evidence, not effort

The big idea

In OCR A Physics, a response can look fluent and still lose a mark because a specific point is missing. A calculation can have the right-looking final answer and still lose credit if the required method has not been shown, or if the physics used is wrong.

OCR mark schemes often use the MACB system: M, A, C and B. You may hear pupils refer to these letters in a different order, such as CMBA, but the meaning is the important part.

The safest exam habit is to show the physics in a way that leaves no doubt. That means writing the key relationship, substituting clearly, using units, explaining cause and effect, and not adding contradictory statements after a correct answer.

02 The mark codes

B, M, C and A marks

Independent mark

A B mark stands on its own. The specific point must be seen in the answer. It is common in definitions, explanations, diagrams and one-step factual points.

Method mark

An M mark is a required method step. If a later A mark depends on this M mark, the A mark cannot usually be awarded unless the method is present.

Compensatory method

A C mark can be implied by later correct working. You do not always need to write the exact equation if your substitution or rearrangement proves you knew it.

Accuracy mark

An A mark is for a correct result or conclusion. It often depends on an M mark or is awarded after enough correct C-mark working has been demonstrated.

03 Mini examples

How marks can be gained or lost

B marks: the missing specific point

Question: Explain why a projectile has constant horizontal velocity when air resistance is negligible. [2]

B1 no horizontal forceB1 so no horizontal acceleration

Pupil answer: It keeps moving forwards because there is no air resistance.

Mark: 1/2. The answer has the no air resistance/no horizontal force idea, but does not explicitly link this to no horizontal acceleration or constant velocity.

M and A marks: answer depends on method

Question: Show that the momentum of a 0.20 kg trolley moving at 3.0 m s^-1 is 0.60 kg m s^-1. [2]

M1 p = mvA1 0.60 kg m s^-1

Pupil answer: 0.60 kg m s^-1

Mark: 1/2 if the answer line alone is accepted for the final value, but the method mark is not shown in a show-that question. Write p = mv = 0.20 x 3.0.

C marks: working can imply the equation

Question: Calculate the kinetic energy of a 0.50 kg object moving at 4.0 m s^-1. [2]

C1 substitution into 1/2mv^2A1 4.0 J

Pupil answer: 0.5 x 0.50 x 4.0² = 4.0 J

Mark: 2/2. The equation was not written, but the substitution proves the pupil knew it.

ECF: one mistake does not always ruin everything

Question: Convert 250 mA to A and calculate V for R = 12 ohm. [3]

B1 0.250 AC1 V = IRA1 3.0 V

Pupil answer: 250 mA = 0.0250 A. V = 0.0250 x 12 = 0.30 V.

Mark: likely 1/3 or 2/3 depending on the scheme. The conversion mark is lost, but the Ohm's law method may still score through error carried forward.

04 Mark scheme language

Words and annotations you need to understand

allow

This response can earn the mark, even if it is not the main wording in the answer column.

ignore

The statement is irrelevant. It does not earn the mark, but it does not stop another correct point scoring.

reject / not

This wording is not acceptable for that mark. If it is the answer offered for the point, the mark is not awarded.

AW

Alternative wording. The pupil does not need the exact phrase if the same physics is clearly communicated.

ORA

Or reverse argument. For example, if increasing one variable causes an effect, the correct opposite statement may also score.

ECF

Error carried forward. Later marks can be awarded if the later working correctly follows from an earlier acceptable error.

AE

Arithmetic error. The method may be correct, but a numerical slip has been made.

TE

Transcription error. A value has been copied incorrectly from the question, graph, formula booklet or earlier working.

POT

Power of ten error, often from prefixes such as milli, micro, kilo or mega. The mark at the error is lost, but later working may still score.

XP

Wrong physics or wrong equation. This is more serious than a numerical slip; later error-carried-forward credit is usually not available from wrong physics.

CON

Contradiction. A correct point may be cancelled if the same response also says something incompatible.

SF

Significant figures. OCR normally allows sensible rounding, but a specific instruction in the question or mark scheme can matter.

BOD

Benefit of doubt. The examiner judges that enough work has been done even though the response is not perfectly expressed.

L1/L2/L3

Level of response bands for 6-mark extended answers. The level depends on the physics and the quality of the line of reasoning.

05 Extended answers

How level-of-response marks work

Look for the asterisk. OCR marks level-of-response questions differently from point-marked questions. The answer is judged by the quality of the physics, analysis and structure rather than by a simple one-tick-per-point list.

For LoR questions, the science content decides the level: Level 1, Level 2 or Level 3. The communication statement then decides whether the answer receives the lower or higher mark within that level. A Level 2 answer with a clear structure can score 4/6; a Level 3 answer with weaker communication may score 5/6 rather than 6/6.

Do not try to write everything you know. Aim for a line of reasoning: method, evidence, analysis and conclusion. For practical questions, say how data are collected, how uncertainty is reduced, how the graph or calculation is used, and why the method answers the question.

06 Interactive assessment

Mark the script

Each card below uses original OCR-style pupil work. Choose the mark you think the response should receive, then check the examiner-style explanation.

Can you spot the hidden lost marks?

Some answers look complete but are missing a B1 point, a required M1 step, or the communication needed for the higher LoR mark.

Score: 0/7

07 Final checklist

How to write answers that survive the mark scheme

For definitions and explanations, include the exact physics point, not just a vague description.
For calculations, write the equation, substitution, answer and unit.
For show-that questions, show the method even if the answer is given in the question.
For multi-step calculations, keep powers of ten and prefixes visible.
Do not add a guess that contradicts your correct point.
Use OCR command words carefully: state, explain, calculate, show that, suggest, compare and evaluate do different jobs.
For LoR questions, build a reasoned answer rather than a list of disconnected facts.