Command Words and Mark Schemes

Two students can know exactly the same mathematics and walk away with very different marks — because one answered the question that was asked and the other answered the question they expected. The difference is reading the command word and understanding how the mark scheme awards credit. On OCR GCSE Mathematics (J560), command words such as "Work out", "Show that", "Give a reason", "Prove", "Write down", "Find" and "Draw" each demand a particular kind of response, and the mark scheme splits credit into method (M) marks, accuracy (A) marks and independent (B) marks. This lesson decodes both so that you give the marker exactly what earns the marks.

Matching your response to the command word is an AO2 skill (interpreting and communicating). Earning method marks by laying out a correct procedure is AO1, and the harder "Show that"/"Prove" tasks reach into AO2 reasoning. The marks in this lesson are some of the easiest to win back, because they reward presentation and reading rather than new mathematics — a student who simply starts showing working and answering the exact command word often gains several marks per paper overnight.

OCR Command Words: What Each One Demands

Command word	What it asks you to do	What earns the marks
Work out	Carry out a calculation to reach an answer	The method and the correct answer; show your working
Calculate	As "Work out" — a numerical result, usually with a calculator on the calc papers	Working plus the accurate value (with units if relevant)
Find	Determine a value or values	The answer, supported by working
Write down	State a result that needs little or no working	The correct value — working is usually not required (and not credited)
Show that	Demonstrate that a given result is true	Every step leading to the stated result; you must reach the given answer
Prove	Establish a general result using rigorous reasoning	A complete logical chain, often algebraic, valid in all cases
Give a reason	Justify a statement or answer in words	A correct mathematical reason, clearly stated
Draw	Produce an accurate diagram, graph or construction	A correct, suitably accurate drawing (use a ruler/pair of compasses)

A few of these deserve extra care:

• "Write down" signals that the answer should come quickly — often from a graph, a table, or a result you have just found. If you find yourself doing heavy working for a "Write down", re-read: there is usually a shortcut, and extra working earns nothing.
• "Show that" gives you the answer in advance. The marks are entirely for the journey. You must arrive at the stated result; if your working leads somewhere else, you have made an error.
• "Give a reason" (and "Explain") means words are required. A bare number scores nothing for the reasoning mark.
• "Draw" (and "Construct") means accuracy with instruments. Use a sharp pencil and a ruler for straight lines, a pair of compasses for arcs and constructions, and a protractor for angles. Freehand sketches lose the accuracy marks. For constructions, leave your construction arcs visible — they are part of what is marked, so do not rub them out.

Worked Example: "Give a reason"

A triangle has angles of $40°$40°, $40°$40° and $100°$100°. Give a reason why this triangle is isosceles.

A reason in words is required, not a calculation: "The triangle is isosceles because it has two equal angles ($40°$40° and $40°$40°), so the two sides opposite those equal angles are also equal." The mark is for stating the property that makes it isosceles — two equal angles (hence two equal sides) — clearly in words. A student who simply writes "isosceles" with no reason earns nothing for the "give a reason" demand.

How Mark Schemes Work: M, A and B Marks

OCR mark schemes (like all GCSE Maths schemes) award three kinds of mark. Knowing them tells you why showing working matters.

Mark type	Stands for	Awarded for
M	Method	Choosing and starting a correct method — even if the final answer is wrong
A	Accuracy	The correct answer, dependent on the relevant method (M) mark being earned
B	Independent	A correct result or statement awarded in its own right, not dependent on method

The crucial consequence: method (M) marks are awarded for correct working even when the final answer is wrong. If you make a slip at the last step but your method was sound, you still bank the M mark(s). If you write only a (wrong) final answer with no working, you score zero. This is the single biggest reason to show your working on every question worth more than one mark.

Note also the dependency between the mark types. An accuracy (A) mark is usually dependent on the corresponding method (M) mark — you cannot earn the accuracy mark for a right answer that appeared by luck without a valid method behind it. A B mark, by contrast, is independent: it is awarded for a correct result or statement in its own right (a correct unit, a correctly read value, a sensible diagram). Knowing this reinforces the same habit from a different angle — visible, correct method is what unlocks both the M marks and the A marks that depend on them.

There is also "follow through" (often written ft): if you make an error early but then use your (wrong) value correctly in later steps, the later accuracy marks can still be awarded on the basis of your earlier figure. Again — only possible if your working is visible.

A short example makes follow-through concrete. Suppose a two-stage question asks you to find the perimeter of a shape after first finding a missing side. If you find the missing side wrongly — say you get $7$7 cm when it should be $8$8 cm — but then add up all the sides correctly using your $7$7, you can still earn the perimeter (A ft) mark for adding correctly, even though your number is wrong. The earlier error costs you one mark, not the whole question. None of this rescue is available if you write only a final number with no working: the marker has nothing to follow through. This is the practical, mark-by-mark reason that "always show your working" is not just neat-handwriting advice — it is how you protect marks against a single slip.

Worked Example: where the marks sit (a 3-mark "Work out")

Work out the area of a triangle with base $9$9 cm and perpendicular height $6$6 cm. (Imagine this is worth 3 marks: M for the method, A for the value, B for correct units — a typical split.)

• Method (M): write the formula and substitute — $\text{Area} = \dfrac{1}{2} \times b \times h = \dfrac{1}{2} \times 9 \times 6$Area=21​×b×h=21​×9×6.
• Accuracy (A): evaluate — $\dfrac{1}{2} \times 54 = 27$21​×54=27.
• Units (B): state $\text{cm}^{2}$cm2.

Answer: $27\text{ cm}^{2}$27 cm2. Even if a student mis-multiplied and wrote $26$26, the M mark (correct formula and substitution) would still be earned. A student who wrote only "$27$27" with no working risks scoring just 1 of the 3.

Showing Working — the Habit That Protects Marks

Make your working a clear, ordered story the marker can follow: