IGCSE Maths Mark Schemes: What Examiners Actually Award Marks For

Cambridge IGCSE Maths mark schemes use a specific system of letter codes that tell examiners exactly what to credit. Understanding these codes transforms how you approach exam questions, because you can work backwards from what earns marks to how you should write your solutions. The three main mark types are: M marks (method marks), awarded for showing a correct mathematical method even if the final answer is wrong; A marks (accuracy marks), awarded for reaching the correct answer, but usually dependent on earning the preceding M mark; and B marks (independent marks), given for a correct result that does not depend on any other mark. For example, a 4-mark question might be structured as M1 A1 M1 A1, meaning two methods each followed by an accuracy mark. If you make an arithmetic error in the first step but apply the correct method, you earn M1 but lose A1 — and crucially, you can still earn M1 A1 for the second step if you follow through correctly with your wrong value. This "follow-through" principle is one of the most powerful features of the Cambridge marking system: it means partial credit is built into the exam design, not left to examiner discretion.

The follow-through (FT) rule is the single most important concept in Cambridge mark schemes that students do not know about. When a mark scheme shows "ft" or "their" (as in "their x value"), it means the examiner will accept your answer based on whatever value you calculated earlier, even if that value was wrong. In practice, this means a single arithmetic error in step one of a five-mark question costs you at most 1-2 marks rather than all 5 — but only if you show clear working for every subsequent step. Consider this example: in a question worth M1 A1 M1 A1 ft A1 ft, if you make an error earning M1 A0 in the first step, the examiner follows your incorrect value through. Your second method step earns M1, and your accuracy marks can still be awarded as A1 ft if your arithmetic with the wrong number is internally consistent. This means you could still score 4 out of 5 despite a wrong answer. However, the follow-through only works if the examiner can follow your method. If you skip steps, use arrows instead of equations, or write working in a scattered way across the page, the examiner cannot identify your method and cannot award follow-through marks. The lesson is clear: always write every line of working, label your steps, and keep your solution flowing logically down the page.

Beyond understanding mark types, several recurring patterns in Cambridge mark schemes catch students by surprise. First, rounding errors are one of the biggest mark killers. The mark scheme typically specifies "3sf" (three significant figures) or an exact answer. If the answer is 4.56 and you write 4.6, you lose the accuracy mark — even though your method was perfect. Always read the instruction line at the top of the paper about rounding, and where the question says "Give your answer correct to 2 decimal places", do exactly that. Second, units matter in certain questions. While most pure maths questions do not require units, any question involving real-world context (speed, area, volume, money) will specify units in the mark scheme, and omitting them costs a B1 mark. Third, "show that" questions require a specific final line that matches the given value. Many students solve these correctly but do not write the concluding statement, losing the final A1. Fourth, graph questions have very specific marking criteria: points must be plotted to within half a small square, curves must be smooth (not straight-line segments between points), and the line of best fit must be reasonable. Losing marks on graph questions is particularly painful because they are often worth 3-4 marks and the errors are purely about technique, not understanding.

The best way to internalise mark scheme logic is to mark your own work. After completing a past paper under timed conditions, download the corresponding mark scheme from the Cambridge website and grade yourself honestly. For every mark you lose, write down whether it was an M, A, or B mark and categorise the reason: method error (did not know the technique), arithmetic slip (knew the method, made a calculation mistake), presentation error (knew the answer but did not communicate it clearly), or reading error (misread the question). After grading five or six papers this way, clear patterns will emerge. Most students discover that they lose far more marks to presentation and arithmetic than to genuine lack of knowledge. A student who consistently loses 8-10 marks per paper to rounding, missing units, and unclear working can often gain a full grade improvement just by being more disciplined about presentation — without learning any new mathematics. This self-marking habit is the single most effective revision technique for IGCSE Maths because it targets the actual marks you are losing rather than topics you might find difficult.