Data & Chance
Representing Data
3rd Class · 4th Class · 5th Class · 6th Class
- ✓By the end of this lesson students will be able to read and interpret information presented in bar charts.
- ✓By the end of this lesson students will be able to draw a simple bar chart from given data.
- ✓By the end of this lesson students will be able to read and interpret information presented in line graphs.
- ✓By the end of this lesson students will be able to read and interpret information presented in pie charts.
- ✓By the end of this lesson students will be able to choose an appropriate graph to display simple data.
Key concepts
A bar chart uses bars of different heights or lengths to show and compare different amounts of data. The bars can be vertical (standing up) or horizontal (lying down).
A line graph uses points connected by lines to show how something changes over time. It's very useful for showing trends, like how temperature changes during the day.
A pie chart is a circle divided into slices, where each slice represents a part of a whole. The size of each slice shows how big that part is compared to the whole. For this lesson, we will only learn how to read and understand pie charts, not how to draw them.
An axis is a line used for measurement on a graph. Bar charts and line graphs usually have two axes: a horizontal axis (often called the x-axis) and a vertical axis (often called the y-axis).
The scale refers to the numbers marked along the axes of a graph. The scale tells us what each mark or line represents and helps us read the values accurately. Choosing a good scale is important so all your data fits on the graph.
A key or legend is a small box on a graph that explains what different colours, patterns, or symbols on the graph mean. It helps you understand what each part of the graph represents.
Key facts to remember
- 1A bar chart uses bars to compare different amounts or categories of data.
- 2A line graph uses points connected by lines to show how something changes over time, often revealing trends.
- 3A pie chart is a circle divided into slices, showing parts of a whole. Each slice represents a proportion of the total.
- 4Always give your graph a clear and informative title.
- 5Label both the horizontal (x-axis) and vertical (y-axis) axes clearly.
- 6Choose an appropriate scale for your axes so that all your data fits and is easy to read.
- 7A key or legend explains what different colours or symbols on a graph represent.
- 8Bar charts are best for comparing distinct categories, while line graphs are best for showing changes over time.
Worked examples
Example 1
The bar chart below shows the favourite colours of students in 4th Class. (Imagine a vertical bar chart with 'Favourite Colour' on the horizontal axis and 'Number of Students' on the vertical axis, with a scale from 0 to 8. Bars are: Red: 7, Blue: 5, Green: 3, Yellow: 2, Purple: 4) a) How many students chose Red as their favourite colour? b) Which colour is the least favourite? c) How many students were surveyed in total?
Answer
a) 7 students b) Yellow c) 21 students
Example 2
Draw a vertical bar chart to show the number of goals scored by a school football team in five matches. Match 1: 3 goals Match 2: 1 goal Match 3: 4 goals Match 4: 2 goals Match 5: 3 goals
Answer
A vertical bar chart with 'Match Number' on the horizontal axis and 'Number of Goals' on the vertical axis (scale 0-5). Bars should be drawn to heights: Match 1 (3), Match 2 (1), Match 3 (4), Match 4 (2), Match 5 (3).
Always use a ruler and pencil to draw neat and accurate graphs. Remember to leave equal spaces between your bars.
Example 3
The line graph shows the temperature in a classroom over a morning. (Imagine a line graph with 'Time' on the horizontal axis (9:00 AM, 10:00 AM, 11:00 AM, 12:00 PM) and 'Temperature (°C)' on the vertical axis (scale 16-22). Points are: 9:00 AM: 18°C, 10:00 AM: 19°C, 11:00 AM: 21°C, 12:00 PM: 20°C) a) What was the temperature at 10:00 AM? b) At what time was the temperature highest? c) How much did the temperature increase between 9:00 AM and 11:00 AM?
Answer
a) 19°C b) 11:00 AM c) 3°C
Line graphs are excellent for showing how data changes continuously over a period of time.
Common mistakes
- ✗Forgetting to label the axes on a bar chart or line graph, making it difficult to understand.
- ✗Not choosing an appropriate scale, which can make the graph too small, too large, or hard to read accurately.
- ✗Not giving the graph a clear title, so the reader doesn't know what the graph is about.
- ✗Drawing bars of unequal width or not leaving equal spaces between bars in a bar chart.
- ✗Misreading the scale when trying to find specific values on a graph, leading to incorrect answers.
Exam tips
- ★Read the question carefully to understand what information you need to find or display.
- ★When drawing a graph, always use a ruler and a sharp pencil to ensure your work is neat and accurate.
- ★Double-check all your labels, scales, and the title after you have finished drawing or interpreting a graph.
- ★Practice reading different types of graphs regularly to become confident in interpreting data quickly and accurately.
Ready to practise?
Try a problem on this topic
Snap a photo or type a question — get step-by-step working instantly.