Every skill together: decide the graph type, the scale, the line and whether a key is needed.
Practice data: A mix of everything: awkward values, decimals, negatives, two data sets, bars and best fit.
Read the question first
Before you draw, decide: bar or line? Which variable goes on x? Does the axis need to start above zero, or below it? One data set or two (is a key needed)? Does the question say "join the points" or "line of best fit"?
Then build the graph in SLAPUK order and mark it. Aim for full marks on each one.
The SLAPUK mark scheme
SLAPUK
Out of 5 (S L A P U). Out of 6 (S L A P U K) when there is more than one data set on the graph.
S
Scale
Even steps of 1, 2, 5 or 10 (×10ⁿ), and the data uses more than half the grid each way. Never use the raw data as your scale.
L
Line
Join the points with straight lines using a ruler, point to point. Best fit only when the question asks.
A
Axes
What you changed goes on x, what you measured goes on y. Copy the table headings as the labels.
P
Plots
Every point within half a small square, drawn as a small × or ⊙.
U
Units
Units after a slash or in brackets: "Time / min" or "Temperature (°C)".
K
Key
Only for two or more data sets: a key that says which line is which.
Practice graphs
1. Rennin and milk
The time for rennin to clot milk was measured at different temperatures.
Plot a graph of time for milk to clot against temperature. Join the points with straight lines using a ruler.[5 marks]
Results Illustrative data
Temperature / °C
Time for milk to clot / s
15
154
22
88
29
47
36
35
43
61
50
140
1 · Axes, labels and scales
Put Temperature / °C (the independent variable) on the x-axis and Time for milk to clot / s on the y-axis. This grid is 8 big squares across and 10 up; each big square has 5 × 5 small squares.
Set your scales, then tap the grid to plot each point.
Keyboard and screen-reader entry
Values are placed using the scale you set, so a wrong scale still gives a wrong graph – just like on paper.
Stuck on the scale?
Range ÷ big squares, then round UP to 1, 2 or 5 (× 10, 100 …). Check the data uses more than half the grid.
