Interpret column graphs & tables
Theory
To read a column graph, find what each step on the scale is worth, then read across from the top of each column. This Year 5 maths page shows how to read values (even between marks), compare columns, and use tables to find totals and differences.
The scale tells you how much each mark is worth. Check the step first: \(2\)s, \(5\)s, \(10\)s or \(20\)s.
If a column stops halfway between two marks, its value is halfway between them: halfway between \(0\) and \(20\) is \(10\).
The tallest column shows the most; the shortest shows the least. A difference is found by subtracting.
A graph only answers questions about what it counts. A graph of how many students chose each club cannot tell you which students chose it.
Rainfall table used in the examples:
| Month | Rainfall (mm) |
|---|---|
| January | \(64\) |
| February | \(118\) |
| March | \(87\) |
| April | \(45\) |
Reading a column graph
- Read the title and axis labels.
- Find the step of the scale.
- Read across from the top of the column; if it is between marks, work out how far.
- Add or subtract values to answer the question.
Halfway between \(80\) and \(100\): \(90\) visitors.
| \(60 + 10 + 90 + 50\) | \(=\) | \(210\) |
\(210\) visitors.
| \(90 - 10\) | \(=\) | \(80\) |
\(80\) more (Wednesday compared with Tuesday).
| \(60 + 50\) | \(=\) | \(110\) |
\(110\) visitors.
(i) Which month was wettest?
(ii) How much more rain fell then than in April?
(iii) What was the total rainfall?
| \(118 - 45\) | \(=\) | \(73\text{ mm}\) |
| \(64 + 118 + 87 + 45\) | \(=\) | \(314\text{ mm}\) |
(i) February
(ii) \(73\) mm
(iii) \(314\) mm
(i) On which day were there most visitors?
(ii) How old were the visitors?
(ii). The graph only shows how many visitors came each day.
(i) How many ice-creams were sold altogether?
(ii) How many more chocolate than mint?
| \(25 + 35 + 10 + 20\) | \(=\) | \(90\) |
| \(35 - 10\) | \(=\) | \(25\) |
(i) \(90\)
(ii) \(25\)
The column stops halfway, so it shows \(10\), not \(20\).
Common pitfalls
Frequently asked questions
How do I read a column that stops between two lines?
Find the halfway value: between \(0\) and \(20\) is \(10\).
How do I find the total from a graph?
Read every column and add the values.
How do I find how many more?
Subtract the smaller value from the larger: \(90 - 10 = 80\).
Which column shows the most?
The tallest one.
Can a graph tell me everything about the data?
No. It only shows what was counted.