IGCSE Physics / Exam technique
Command words: what each question wants
Edexcel International GCSE Physics (4PH1), chapter 30: Exam technique, specification point CW. Free lesson.
Read the revision notes · IGCSE Physics past papers
A command word tells you what kind of answer the question needs. Matching your answer to it helps you gain marks without adding unnecessary words.
What the main command words ask for
The command word is usually the first word of a question. It tells you whether to give a fact, describe events, explain reasons, do a calculation, make a drawing or reach a judgement. State, name and give need a short fact, with no reasons or working. Describe asks what happens, usually in order. Explain and suggest ask why, with reasons linked to the situation. Calculate, determine, estimate and show that ask for a number and working, though each has a different focus. Plot, sketch and draw ask for a graph or diagram, with different…
How to tell describe from explain
Describe reports what happens. Explain links what happens to the reason why. The same situation can need either kind of answer, depending on the command word. For a skydiver falling before opening her parachute, a description is: her speed increases, then becomes constant. An explanation gives the reason: her weight is bigger than air resistance at first, so there is a resultant force downwards and she accelerates. A describe answer does not need linking words. An explain answer should link ideas with words such as because, so or which means. If your explain answer has no…
What calculation command words need
All the number command words need working, but they do not all ask for the same kind of result. Show how you reached your answer, not just the final number. Calculate needs a number, working and a unit. Determine needs a number and may require a method such as finding a gradient from a graph. A gradient is the steepness of a line. Show that gives you the answer to reach, so marks are for the working. Give one more figure than the value shown, and do not use the value you are proving in your working. Estimate asks for a rough value, which you can find by rounding the…
How carefully to plot, sketch or draw
These words set how precise your graph or diagram must be. Check the command word before you start, because each has different marking points. Plot points accurately, within half a square, then draw a line of best fit. Marks are available for the crosses and the line. Sketch the correct shape on labelled axes. You do not need a scale, but include the shape and key points. Draw an accurate diagram using a ruler. Marks can be for ruled lines, arrows and labels. An unlabelled sketch earns nothing, even if its shape is correct.
How to comment on data and reach a judgement
Comment on needs a judgement, and the judgement must be supported by the data. A strong answer uses the evidence, says what it shows, then gives a conclusion.
Start with the answer, not the question
Repeating the question at the start does not show extra physics. The question's words are already on the paper, so repetition uses time and space without earning a mark. For a car travelling at constant speed on a flat road, the driving force equals the resistive forces, so the resultant force is zero. With no resultant force there is no acceleration, so the speed does not change. Start with the first point that answers the question.