The idea in brief. Each equal space on the axis represents the same amount. Count the spaces between marked values before reading a bar. In the lesson. In Primary 2, you read picture graphs, where one picture could stand for two things. Today, we learn to read a bar graph using its scale. The bar graph shows the number of seed packets packed by four gardening groups. How many packets did Group C pack? First find what one space stands for. Then count on from the numbered line below. Each equal space on the axis represents the same amount.
Lesson video, with the working
Reading a bar graph and its scale
5 min 33 s
The film teaches 2 questions in turn. Each question shows first; its working is written as the film explains it.
What is the first step in reading a bar graph with a scale in P3?
Primary 3 is where bar graphs begin, after picture graphs with scales in Primary 2.
What your child learns here
Primary 3 is where bar graphs begin, after picture graphs with scales in Primary 2. This page covers both syllabus outcomes for the topic: reading and interpreting data from bar graphs, and using different scales on the axis. Bars may stand upright or lie across the page.
Read the title and axis labels to know what is being counted.
Find what one space on the axis stands for by dividing a numbered value by the spaces below it.
Read a bar that stops between numbered lines by counting on from the line below.
Read a horizontal bar graph the same way, along its scale.
Pick out the greatest and smallest from the lengths of the bars.
Does the answer make sense?
A reading must sit at or between the two numbered lines nearest the bar's end, and a longer bar must give a larger number than a shorter one. When the question asks which station had the greatest number, your child simply picks out the longest bar.
How to practise these questions
The Basic question practises reading a bar against its scale. The Intermediate questions add scales that go up in steps larger than 1, so a bar may end between two marked lines. The Challenge question gives only the value of one small space, so your child works out every bar's reading before adding them all together. If reading a graph stalls, watch that question's solution film and try it again later from Revision. There are also multiple-choice questions: at Basic, which group has the most or the fewest, and at Intermediate, which statement about a difference or a total read from the graph is true, each with written working instead of a film.
Questions parents ask
Are bar graphs in the Primary 3 syllabus? Yes. The P3 syllabus lists bar graphs under Statistics, with two outcomes: reading and interpreting data from bar graphs, and using different scales on the axis.
What does 'scale' mean on a bar graph? The scale is the numbering on the axis. Each space between lines stands for the same amount, which may be 1, 2, 5, 10 or another number, and the reader works it out from the numbers shown.
How is a bar graph different from a picture graph? In Primary 2 picture graphs with scales, each picture can stand for more than one item. A bar graph uses the length of a bar against a numbered axis instead, so the value of each space has to be worked out.
