Statistics
Charts & Graphs
Year 3 · Year 4 · Year 5 · Year 6
- ✓By the end of this lesson students will be able to interpret and present data using bar charts and pictograms.
- ✓By the end of this lesson students will be able to interpret and present discrete and continuous data using line graphs.
- ✓By the end of this lesson students will be able to interpret and construct simple pie charts to represent proportions.
- ✓By the end of this lesson students will be able to solve comparison, sum, and difference problems using information from various charts.
Key concepts
A bar chart uses rectangular bars to show the values of different categories. The length or height of each bar is proportional to the value it represents. Bars can be vertical or horizontal. In a bar chart, there should be equal gaps between bars and the bars themselves should be of equal width. The axes must be clearly labelled, and an appropriate scale chosen.
A pictogram uses pictures or symbols to represent data. Each symbol represents a certain quantity, which is explained in a 'key'. It is important to use the key correctly, especially when symbols are cut in half or quarters to show partial quantities.
A line graph shows how data changes over time. Points are plotted on a grid and then joined with straight lines. The horizontal axis (x-axis) usually represents time, and the vertical axis (y-axis) represents the quantity being measured. Line graphs are best for showing continuous data, such as temperature changes over a day.
A pie chart is a circular chart divided into sectors, where each sector represents a proportion of the whole. The entire circle represents the total amount of data. Larger sectors mean a larger proportion of the total. For Key Stage 2, we often interpret simple fractions like half, quarter, or third of the total amount.
Key facts to remember
- 1Bar charts use bars to compare quantities across different categories.
- 2Pictograms use pictures or symbols, with an essential key to show what each symbol represents.
- 3Line graphs show how data changes over time and are best for continuous data.
- 4Pie charts show parts of a whole, with the entire circle representing the total amount.
- 5Always label your axes clearly on bar charts and line graphs, and give your chart a title.
- 6Choose an appropriate scale for your axes to make the data easy to read and interpret.
- 7The 'key' in a pictogram is crucial for understanding the data and calculating values.
- 8Data can be discrete (counted, e.g., number of children) or continuous (measured, e.g., temperature).
Worked examples
Example 1
The bar chart below shows the favourite fruits of a Year 4 class. (Imagine a bar chart with 'Fruit' on the x-axis and 'Number of Children' on the y-axis, scaled 0-10. Bars are: Apple: 8, Banana: 6, Orange: 4, Grape: 2) a) How many children chose Apple as their favourite fruit? b) How many more children prefer Banana than Grape? c) How many children were surveyed in total?
Answer
a) 8 children b) 4 children c) 20 children
Example 2
The line graph below shows the temperature in a classroom over a day. (Imagine a line graph with 'Time' on the x-axis (9am, 10am, 11am, 12pm, 1pm, 2pm, 3pm) and 'Temperature (°C)' on the y-axis (scaled 15-25). Points are: (9am, 18°C), (10am, 19°C), (11am, 20°C), (12pm, 21°C), (1pm, 20°C), (2pm, 19°C), (3pm, 18°C)) a) What was the temperature at 11am? b) At what time was the temperature highest? c) Between which two times did the temperature decrease?
Answer
a) 20°C b) 12pm c) Between 12pm and 1pm, 1pm and 2pm, and 2pm and 3pm.
Example 3
A class of 32 children voted for their favourite colour. The pie chart below shows the results. (Imagine a pie chart where half of the circle is labelled 'Blue', a quarter is labelled 'Red', and the remaining quarter is labelled 'Green') a) How many children chose Blue? b) How many children chose Green? c) How many more children chose Blue than Red?
Answer
a) 16 children b) 8 children c) 8 children
Pie charts show proportions of a whole. The entire circle represents the total amount of data.
Common mistakes
- ✗Not reading the scale or key correctly, leading to incorrect values when interpreting data.
- ✗Forgetting to label axes or give a title to the chart, making it difficult to understand.
- ✗Drawing bars of different widths or with unequal gaps in a bar chart, which can be misleading.
- ✗Joining points on a line graph when the data is not continuous (e.g., favourite colours should be a bar chart).
- ✗Misinterpreting simple fractions or percentages when reading a pie chart.
Exam tips
- ★Always read the question carefully and look at all parts of the chart (title, axes, labels, key) before answering.
- ★Use a ruler to draw straight lines and to read values accurately from scales on axes.
- ★Check your calculations, especially when finding totals, differences, or proportions.
- ★Make sure your answers are in the correct units (e.g., °C, number of children, cm).
Ready to practise?
Try a problem on this topic
Snap a photo or type a question — get step-by-step working instantly.