Measurement, Geometry & Data
Everyday Statistics: Pictograms and Bar Charts
Primary 4 · Primary 5 · Primary 6
- ✓By the end of this lesson students will be able to define data and statistics in simple terms.
- ✓By the end of this lesson students will be able to read and interpret information presented in pictograms.
- ✓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 simple pictograms from given data.
- ✓By the end of this lesson students will be able to draw simple bar charts from given data.
Key concepts
Data is a collection of facts or information. For example, the number of students in a class, the types of fruits people like, or the number of cars sold in a month are all examples of data.
Statistics is the study of how to collect, organise, show, and understand data. It helps us make sense of information around us.
A pictogram is a chart that uses pictures or symbols to represent data. Each picture or symbol stands for a certain number of items. This number is shown in a 'key'. Pictograms make it easy to compare quantities visually.
A bar chart is a chart that uses rectangular bars of different heights or lengths to show data. The height or length of each bar shows the quantity or frequency of an item. Bar charts have two axes: a horizontal axis and a vertical axis, and a scale to help read the values.
Key facts to remember
- 1Data is information collected for a purpose.
- 2Statistics helps us organise and understand data.
- 3Pictograms use pictures to represent data, and they always have a key.
- 4A key in a pictogram tells you what each picture symbol stands for.
- 5Bar charts use rectangular bars to show data, with the height or length of the bar indicating quantity.
- 6Bar charts have a horizontal axis, a vertical axis, and a scale.
- 7Charts and graphs make it easier to compare and interpret data visually.
Worked examples
Example 1
The pictogram below shows the number of oranges sold by a fruit seller over four days.\n\nKey: = 10 oranges\n\nMonday: \nTuesday: \nWednesday: \nThursday: \n\na) How many oranges were sold on Tuesday?\nb) On which day were the most oranges sold?\nc) What is the total number of oranges sold from Monday to Thursday?
Answer
a) 30 oranges\nb) Wednesday\nc) 140 oranges
Always check the 'Key' in a pictogram first to know what each picture represents.
Example 2
The bar chart below shows the favourite colours of pupils in a Primary 5 class.\n\n[Imagine a vertical bar chart here with 'Colour' on the horizontal axis (Red, Blue, Green, Yellow) and 'Number of Pupils' on the vertical axis (0 to 10, with increments of 1).]\n\nBar heights:\nRed: 8 pupils\nBlue: 10 pupils\nGreen: 5 pupils\nYellow: 3 pupils\n\na) How many pupils chose Blue as their favourite colour?\nb) Which colour is the least favourite?\nc) How many more pupils prefer Red than Yellow?
Answer
a) 10 pupils\nb) Yellow\nc) 5 pupils
Carefully read the scale on the vertical axis to get accurate values.
Example 3
A survey was conducted in a Primary 6 class to find out the number of siblings each pupil has. The results are shown in the table below:\n\nNumber of Siblings | Number of Pupils\n-------------------|------------------\n0 | 2\n1 | 7\n2 | 5\n3 | 3\n\nDraw a bar chart to represent this data.
Answer
A correctly drawn vertical bar chart with:\n- Title: 'Number of Siblings of Primary 6 Pupils'\n- Horizontal axis labelled 'Number of Siblings' with categories 0, 1, 2, 3.\n- Vertical axis labelled 'Number of Pupils' with an appropriate scale (e.g., 0 to 8 or 10, marked at 1-unit intervals).\n- Bars of equal width and spacing, with heights corresponding to the data: 2 for 0 siblings, 7 for 1 sibling, 5 for 2 siblings, and 3 for 3 siblings.
Use a ruler and pencil to draw neat and accurate bar charts. Always label your axes and give your chart a title.
Common mistakes
- ✗Not checking the key in a pictogram, leading to incorrect calculations.
- ✗Misreading the scale on the vertical axis of a bar chart.
- ✗Forgetting to label the axes of a bar chart when drawing it.
- ✗Drawing bars of different widths or unequal spacing in a bar chart.
- ✗Not giving a title to the pictogram or bar chart.
Exam tips
- ★Always read the question carefully to understand what information is being asked.
- ★For pictograms, always identify and use the key correctly for all calculations.
- ★For bar charts, pay close attention to the labels on both axes and the scale on the vertical axis.
- ★When drawing charts, use a ruler and a sharp pencil to ensure neatness and accuracy. Label everything clearly.
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