Draw graphs that score every mark.
Eight short lessons on exam-style grid paper. Start with SLAPUK, then practise the hardest part: choosing a scale. The data gets steadily harder, from 10, 20, 30 to awkward values like 11, 47 and 116.
Start lesson 1: SLAPUKFor KS3, GCSE/IGCSE and A level. Your graphs stay in this browser tab: nothing is saved or sent anywhere.
The lessons
- 1SLAPUK: build a graph step by stepThe six things a graph is marked on, and the order to draw it in.Data: Tidy values that fit the grid easily.
- 2Choosing a scaleThe method that works every time, and the mistakes that lose the S mark.Data: Values that need a little thought: 5s, 20s and 50s.
- 3Tidy data: 10, 20, 30Round numbers, but different ranges: practise picking 5, 10, 20, 50 or 100 per big square.Data: Round values (10, 20, 30 …) with ranges that need different steps.
- 4Awkward values: 11, 47, 116Uneven numbers that tempt you to use the data as the scale. Choose the scale from the range instead.Data: Irregular values such as 11, 47, 116, and uneven gaps between x values.
- 5Decimals and axes that do not start at zeroSmall decimal values, and data bunched far from zero where a non-zero start is the right choice.Data: Decimals (0.14, 2.4) and data such as 78–148 or 84.1–85.6.
- 6Negative values and two lines on one graphAxes that cross zero, and two data sets on the same axes with a key (the K mark).Data: Values below zero, and pairs of data sets.
- 7Bar or line? Lines and curves of best fitBar charts for categories, line graphs for continuous data, and what to do when a question asks for best fit.Data: Categories, and data that asks for a line or curve of best fit.
- 8Mixed challengeEvery skill together: decide the graph type, the scale, the line and whether a key is needed.Data: A mix of everything: awkward values, decimals, negatives, two data sets, bars and best fit.
How a graph is marked: 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.
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.
Line
Join the points with straight lines using a ruler, point to point. Best fit only when the question asks.
Axes
What you changed goes on x, what you measured goes on y. Copy the table headings as the labels.
Plots
Every point within half a small square, drawn as a small × or ⊙.
Units
Units after a slash or in brackets: "Time / min" or "Temperature (°C)".
Key
Only for two or more data sets: a key that says which line is which.
Try the graph paper
1. Pondweed and a lamp
A student moved a lamp away from some pondweed and counted the bubbles of oxygen given off in one minute.
Plot a graph of rate of photosynthesis against distance from lamp. Join the points with straight lines using a ruler. [5 marks]
| Distance from lamp / cm | Rate of photosynthesis / bubbles/min |
|---|---|
| 10 | 48 |
| 20 | 36 |
| 30 | 24 |
| 40 | 16 |
| 50 | 10 |
1 · Axes, labels and scales
Put Distance from lamp / cm (the independent variable) on the x-axis and Rate of photosynthesis / bubbles/min 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?
x: 50 ÷ 8 → 10 per big square. y: 48 ÷ 10 → 5 per big square.