What is the actual difference between 'describe' and 'explain' in a biology answer?
Describe says what happens. Explain says why it happens. The difference is worth more marks in this subject than almost any piece of content, and it is the most…
Worked answers to exam questions
Real questions, worked through step by step, with the method a mark scheme rewards and the specific place most students lose marks. Not answer keys: the point is the working, because the answer on its own teaches nothing.
- 12 worked answers
- 8 subjects
- Free to read
Biology
Often chosen as the least mathematical science and then found to be the most demanding in written technique. Biology has an enormous factual base, but the marks are awarded for applying it to unfamiliar contexts in precisely worded answers.
Chemistry
Three subjects wearing one name: physical chemistry is applied maths, inorganic is largely patterns and recall, and organic is a language with its own grammar. Students are rarely equally strong in all three, and treating them as one subject is why revision underperforms.
How do I predict which way an equilibrium shifts when conditions change?
Le Chatelier's principle: the system shifts to oppose the change imposed on it. The principle is easy. The marks are in saying why the shift happens in the terms of…
How do I work out concentration when the question gives me a mass and a volume?
Always through moles. Mass and volume never connect directly, and trying to make them is the single most common reason these questions go wrong.
Computer Science
The programming-and-theory route: how machines represent and move data, plus writing and tracing algorithms by hand and at a keyboard. The exam tests a narrower, more precise skill than the one most keen programmers have been practising.
I wrote working Python and got half marks. Why?
Because the paper asked for pseudocode and marks the structure, not whether the code would run. A correct Python answer can miss several structural marks while…
Why does my trace table always go wrong on the last iteration?
Because you are almost certainly checking the condition at the wrong moment, and the last row is the only place that difference shows up.
How do I write a negative number in two's complement without getting confused?
There is a two-step method that always works, and most of the confusion comes from students half-remembering a third step that does not exist.
Economics
Two subjects in one: diagrams that must be drawn precisely and labelled correctly, and essays that must reach an argued judgement. Students are usually comfortable with one half and losing most of their marks in the other.
If a firm raises its price, does revenue go up or down?
It depends entirely on price elasticity of demand, and that is the whole point of the question. An answer that picks a direction without naming elasticity has…
English Language
Reading comprehension, directed writing and composition. The marks are technical (for structure, register and controlled accuracy) which is why a student who reads widely and writes fluently can still sit at a grade 6.
I name the technique and still lose marks. What does 'analyse the effect' actually want?
It wants the specific thing that this word does to this reader in this sentence. Naming the device identifies the tool. The marks are for what the tool was used to…
ICT
The applied route: spreadsheets, databases, document production and web authoring to a professional standard, plus understanding how technology is used in organisations. Most of the grade is earned at a computer.
Why does my VLOOKUP return #N/A when the value is clearly in the table?
Four causes, and in a practical exam it is nearly always the fourth. Work through them in order rather than retyping the formula and hoping.
Mathematics
The subject where gaps compound. Every topic rests on an earlier one, so a weakness in algebra from Year 9 quietly becomes a weakness in calculus in Year 12, and the student experiences it as "I am bad at maths" rather than "I missed one thing."
How do I know whether to use the chain rule, product rule or quotient rule?
Look at how the expression is built, not at what functions appear in it. The rule you need is decided by the structure, and there is a three-question test that…
How do I show a quadratic has two distinct roots without solving it?
Use the discriminant, and state the conclusion in the form the mark scheme wants. Most students get the arithmetic right here and lose the mark on the final line.
Physics
The most mathematical of the sciences and the one where students most often understand the concept and still lose the marks. Physics rewards precise definitions, correct units and the ability to turn a described situation into an equation.
A 1200 kg car has a driving force of 4000 N and 1600 N of resistance. What is its acceleration?
2.0 m/s². The whole question is one idea: find the resultant force first, then apply F = ma. Most lost marks here come from skipping the first word.
How to use these properly
Attempt the question first, under something close to exam timing, and mark your own attempt against the published mark scheme before you read the worked answer. That order matters more than it sounds. Reading a solution produces the feeling of understanding; attempting one and then seeing where your version diverged produces the actual thing.
Every answer here is written the way we would teach it in a lesson, which means it spends more time on the decision points than on the arithmetic. The arithmetic is rarely where the marks go.