What a marked paper actually looks like

Every centre says it marks past papers. Here is the thing itself: three questions, a student's own working, every mark accounted for, and the plan that goes back with it.

IGCSE · Mathematics and Physics Paper sat to time Returned in 48 hours First one free

The questions below are written in the style of the papers rather than copied from one, and the student is invented. What is real is the marking: the two ways marks are most often lost, and what is said about them.

Question 1 — the answer to a different question

3 of 5 marks

A rectangular garden is 3 m longer than it is wide. Its area is 88 m². Find the perimeter of the garden. [5]

Let width = w
w(w + 3) = 88M1 ✓
w² + 3w − 88 = 0M1 ✓
(w + 11)(w − 8) = 0
w = 8   (w ≠ −11)A1 ✓
length = 8 + 3 = 11
Answer: 11 mM0 A0 ✗

3 / 5

The hard part is completely correct — the equation, the rearrangement, the factorising, the right root chosen for the right reason. Then the question asked for the perimeter and the answer given was a length. Two marks gone at the last line, and nothing in a revision guide would ever have caught it. 2(8 + 11) = 38 m.

Question 2 — rounded in the middle

1 of 2 marks

A cylinder has radius 4.2 cm and height 9.5 cm. Calculate its volume, correct to 3 significant figures. [2]

V = πr²h
r² = 4.2² = 17.6← rounded
V = π × 17.6 × 9.5M1 ✓
  = 525.27…
Answer: 525 cm³A0 ✗

1 / 2

The method is right and earns its mark. The answer is wrong by one in the third figure, and the whole cause is on the second line: 4.2² is 17.64, not 17.6. Round once, at the end. π × 17.64 × 9.5 = 526.47… = 526 cm³.

Question 3 — the unit that was never converted

1 of 3 marks

An electric heater is rated at 2.0 kW. It is switched on for 5.0 minutes. Calculate the energy it transfers. [3]

E = P × tM1 ✓
P = 2.0    t = 5.0← kW, minutes
E = 2.0 × 5.0M0 ✗
  = 10
Answer: 10 kJA0 ✗

1 / 3

Nothing here is a physics mistake. The equation is the right one, chosen for the right reason, and it earns its mark. What went are the two conversions the equation quietly assumes — watts, and seconds. 2.0 kW is 2000 W; 5.0 minutes is 300 s. E = 2000 × 300 = 600 000 J = 600 kJ. The answer written down is out by a factor of sixty, and every bit of the physics behind it was right.

And this is what goes back with it

A score on its own changes nothing. Four specific things, in the order they matter, and the next lesson starts on the first of them.

Underline what the question asked for, before you start Every question, every time, for the next two weeks. This one habit was worth two marks here, and it costs nothing.

Keep every figure until the final line Use the calculator's memory rather than writing a rounded number down and typing it back in. We will do ten of these in the next session, with a stopwatch.

Quadratics are secure — leave them This is worth saying plainly, because most revision time is spent on what is already safe. Nothing in Question 1's method needs practice. Spend that time on mensuration instead.

Write the units into the substitution, not onto the answer Every line of a physics calculation, for the next two weeks: the number and its unit together. A wrong power of ten almost always shows itself the moment the units are standing beside it.

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