How to Answer IGCSE Physics Paper 6 (Alternative to Practical)

Paper 6 tests practical skills without requiring a laboratory. It assesses your ability to plan experiments, record data, plot graphs, analyse results and evaluate methods. The paper is worth 40 marks and lasts 1 hour.

Section structure

Paper 6 typically contains 4 to 5 questions, each based on a different experiment. Questions progress from straightforward data recording to more demanding analysis and evaluation.

Data recording

When recording measurements:

• Use the correct number of decimal places (match the precision of the measuring instrument).
• Include units in column headings (e.g., “Length / cm”).
• If asked for repeat readings, record all individual values and calculate the mean.
• Check that your readings are consistent. If one reading is very different from the others, note it as anomalous.

Table construction

When asked to draw a results table:

• Draw the table with a ruler.
• Include column headings with quantities and units.
• Align decimal points in each column.
• Include columns for calculated values if the question requires them.

Graph plotting

Marks are awarded for:

• Axes: correctly labelled with quantity and unit, appropriate scale that uses at least half the grid.
• Points: plotted accurately (within half a small square).
• Line of best fit: smooth, passing through or close to the majority of points. Do not join dots unless specifically asked.

Gradient calculation

1. Choose two points on the line of best fit (not data points unless they lie exactly on the line).
2. The two points should be far apart to reduce error.
3. Show the triangle on the graph.
4. Calculate gradient = (y2 - y1) / (x2 - x1).
5. Include the unit.

Evaluation questions

When asked to evaluate an experiment:

• Identify sources of error (random and systematic).
• Suggest specific improvements (not “be more careful” but “use a light gate instead of a stopwatch to reduce reaction time error”).
• If asked whether the results support a hypothesis, refer to the data and the graph.

Time management

With 40 marks in 60 minutes, you have 1.5 minutes per mark. Graph plotting often takes longer, so budget extra time for those questions. Do not spend 15 minutes perfecting a graph when 5-mark evaluation questions remain.