1. Mathematics Lesson 2: Dual bar charts

2. how to interpret dual bar charts
Learning Intentions
We are learning…
about dual bar charts, their features and the types of data which suit dual bar charts
how to interpret dual bar charts
how we can use dual bar charts in real life and when exploring topics in other subjects
AfL
Share these AfL learning intentions with pupils in your introduction to the lesson.
Share and negotiate success criteria with pupils.

3. Features of dual bar charts
A dual bar chart compares data for two categories – for example men and women, Belfast and Dublin, or under 18s and over 18s.
It always has a key to show which category is which.
The bars for the two categories are side by side. There is a space between each pair of bars and the next pair.
AfL
This part of the lesson uses the following strategies:
scaffolding reflection by asking for feedback from pupils.
Make sure that pupils understand the term key in relation to charts.
Ask pupils the following question:
Can you think of other categories that you could compare in a dual bar chart?

4. Exercise dual bar chart
Percentage of children getting enough exercise
Talk through the characteristics of a dual bar chart with pupils.
They will interpret this particular bar chart in the next slide.

5. Interpreting dual bar charts (1)
Look at the Exercise dual bar chart (Resource 2a). Compare the heights of the bars for each age group.
AfL
This part of the lesson uses the following strategies:
effective questioning; and
scaffolding reflection by asking for feedback from pupils.
Give pupils a copy of Resource 2a, which shows the exercise dual bar chart from the previous slide.
Ask pupils to answer the questions on the slide relating to this chart.
Then, ask pupils the following question:
Overall, what comment would you make about how much exercise children in the UK take?

6. Reading habits of 16 year olds
Review and discuss this dual bar chart with pupils.

7. Interpreting dual bar charts (2)
We asked 16 year olds about their reading habits over the past 4 weeks. The chart displays types of texts that they read at least once in those four weeks. It also shows the percentage of boys and girls who read these different texts. Look at the Reading dual bar chart (Resource 2b).
AfL
This part of the lesson uses the following strategies:
effective questioning; and
scaffolding reflection by asking for feedback from pupils.
Give pupils a copy of Resource 2b, a chart which displays reading habits of 16 year olds.
Ask them to answer the questions on the slide.

8. Continued Look at the Reading dual bar chart (Resource 2b). AfL
This part of the lesson uses the following strategies:
effective questioning; and
scaffolding reflection by asking for feedback from pupils.
Give pupils a copy of Resource 2b, a chart which displays reading habits of 16 year olds.
Ask them to answer the questions on the slide.

9. Interpreting dual bar charts: model answer
For this sample:
Magazines were the most popular reading material for both boys and girls, but there was a large difference in the percentage who read them - 67% of girls and 47% of boys. This could be because most magazines for this age group are designed to appeal to girls, but you would need more data to support this assumption.
AfL
This part of the lesson uses the following strategies:
effective questioning; and
scaffolding reflection by asking for feedback from pupils.
Thinking Skills and Personal Capabilities
In Worksheet 2, pupils have the opportunity to develop the following skills:
Thinking, Problem-Solving and Decision-Making;
Managing Information; and
Being Creative.
Show pupils the model answer for the reading dual bar chart (Resource 2b).
Make sure they understand the term ‘assumption’ in relation to bar charts.
Ask them whether they can tell from the bar chart whether boys or girls read more.
The answer should be that you can’t tell from the chart. The 16 year olds weren’t asked how long or how often they read different materials, just whether they read them at least once in the 4 week period.
Give pupils copies of Worksheet 2 and ask them to complete it.

10. Interpreting dual bar charts: model answer
Girls read more fiction than boys (53% against 43%).
Boys read slightly more non-fiction and newspapers than girls.
Both boys and girls read magazines more than comics. This could be because most comics appeal to a younger age group. However, you would need more data to support this assumption.
AfL
This part of the lesson uses the following strategies:
effective questioning; and
scaffolding reflection by asking for feedback from pupils.
Thinking Skills and Personal Capabilities
In Worksheet 2, pupils have the opportunity to develop the following skills:
Thinking, Problem-Solving and Decision-Making;
Managing Information; and
Being Creative.
Show pupils the model answer for the reading dual bar chart (Resource 2b).
Make sure they understand the term ‘assumption’ in relation to bar charts.
Ask them whether they can tell from the bar chart whether boys or girls read more.
The answer should be that you can’t tell from the chart. The 16 year olds weren’t asked how long or how often they read different materials, just whether they read them at least once in the 4 week period.
Give pupils copies of Worksheet 2 and ask them to complete it.