The right chart depends on what relationship the data shows: a trend over time, a comparison between categories, a share of a whole, or a link between two numbers. Practical tasks usually say “create a suitable chart”, and you must justify the choice by labelling it well.
This lesson follows separating inputs, calculations and outputs and belongs to the module on spreadsheet modelling and charts.
Which chart fits which relationship?
| Question the data answers | Chart type |
|---|---|
| How does a value change over ordered time? | Line chart |
| Which category is bigger or smaller? | Column or bar chart |
| What share of a total does each part take? | Pie chart, few slices only |
| Do two numeric measures move together? | Scatter chart |
Decide the relationship first, then pick the chart. Never start from how the chart looks.
How to build the chart, step by step
- Select only the cells needed: the labels and the values, without totals unless the totals are the point.
- Choose the chart type from the table above.
- Add a title that says what the chart shows.
- Label both axes, including units such as RM or kg.
- Add a legend only when there is more than one series, and remove clutter such as heavy gridlines.
- Check the chart against the data by reading two values off it and comparing them with the table.
Worked example
The invented classes 4A, 4B, 4C and 4D sold these numbers of raffle tickets: 12, 18, 9 and 21.
Step 1, relationship: the classes are separate categories, and the task asks “which class sold the most”. That is a comparison, so a column chart fits.
Step 2, total: 12 + 18 + 9 + 21 = 60 tickets.
Step 3, if a share is asked instead: 12/60 = 20%, 18/60 = 30%, 9/60 = 15%, 21/60 = 35%. These add to 100%, so a pie chart with four slices is also readable.
Step 4, labels: title “Raffle tickets sold by class”, horizontal axis “Class”, vertical axis “Tickets sold”.
Step 5, read-back: the tallest column is 4D at 21, and the shortest is 4C at 9. That matches the table.
The mistake to watch for
A common slip is to use a line chart for separate categories.
Mistaken chart: a line joining 4A, 4B, 4C and 4D.
The line rises and falls between classes, which suggests that something happens “between” 4A and 4B. Nothing does.
The correction is a column chart. A line belongs only where the points on the horizontal axis follow an order, such as hours of the day or months of the year. Also check that axis titles are present, because a correct type with no labels still loses marks.
Check yourself
1. The temperature of a classroom is recorded at 8 am, 9 am, 10 am, 11 am and 12 pm. Which chart, and why?
Show answer
A line chart. The times are ordered, and the question is about change over time.
2. Eight students record hours of revision and test score. You want to see whether more revision goes with higher scores. Which chart?
Show answer
A scatter chart. Both measures are numbers, and you are looking for a link between them.
3. A canteen sold 40 nasi lemak, 25 mee goreng and 35 sandwiches. What percentage is mee goreng, and which chart shows the shares?
Show answer
Total = 40 + 25 + 35 = 100, so mee goreng is 25%. A pie chart with three slices shows the shares.
Where this leads next
Charts only look right when the numbers behind them are formatted well, so go next to format units without converting numbers to text. The spreadsheet reference practice grid lets you try chart data on a small table.
If a task mark scheme keeps asking for “suitable” and you cannot tell what that means, a teacher in online one-to-one ICT tuition can show you how the wording maps to choices on the page.