Question 1 of every 9702 Paper 3 ends with the same graph: up to six marks for axes, plotting, the line, the gradient and the intercept. This trainer gives you fresh readings each time, marks every step the way an examiner would, and shows you how to fix what you got wrong. Use Guided to learn with hints and animations, then Exam mode to test yourself without help.
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Each axis is labelled with the quantity and unit (for example T² / s²). The scales make the points cover at least half the grid both across and up, are labelled at least every large square, and avoid awkward steps such as 3, 6, 7 or 9 per large square. A false origin is fine, and often needed.
Every point is within half a small square of its true position, drawn as a small neat cross or dot. A blob wider than half a small square loses the mark.
One thin straight line, drawn with a ruler, with a fair balance of points on each side across the whole range. Never join dot to dot, and never force the line through the origin.
Use a triangle whose hypotenuse is at least half the length of your line. Read its corners from the line (not from the data table) to within half a small square, and show Δy / Δx.
Read it directly only if the x-axis starts at zero. With a false origin, where the line meets the left edge is not the intercept: substitute a point on the line into y = mx + c.
In Paper 5, draw error bars from the uncertainties, then the steepest or shallowest straight line that still passes through every bar.
Uncertainty = |best gradient − worst gradient|. The same idea gives the uncertainty in the intercept.
The marking follows the conventions in published Cambridge mark schemes. The experiments, readings and wording on this page are our own.