Numerical data can be of two types: ‘discrete’ and ‘continuous’. Discrete data is counted, whereas continuous data is measured.
Preparation
Once again, this activity is best done outside the classroom for reasons of space. You will need a way to measure heights, for example a stick about 2 m long marked in cm.
This activity will provide good opportunities for you to use questioning to promote your students’ thinking. As part of your planning, you can use Resource 2 to help you think about how you will use questioning during the activity.
Use a group of about 20 students so that there are enough to divide up into categories but not so many that what you are illustrating becomes obscured.
The activity
Now move back to the classroom.
![]() Video: Using questioning to promote thinking |
My class contained 63 students, so I asked 26 of them to come forward, taking care to see a wide range of heights was represented. The rest were asked to stand back and help make the observations and note down the discussions.
The discussion on why they could not be represented as bar graphs was heated and extremely participatory. Mohit said that it would seem we will have to make 26 bars when one of the students said that they could very well be represented as a bar each in a histogram if the measuring was carried out extremely accurately.
Then there was a discussion on how many groups we could make, whether there was a restriction or rule by which we could decide. That was when we talked about how the range could help us decide on this. Some wanted the class interval size to be 3 cm, and some were for having it 5 cm. Ultimately I asked them to do what they felt was right and to actually make the groups and see how they worked when shown on the paper. So we made a line and measured all the 26 students for their heights.
I asked them to form groups of four for putting the data on a proper form by using the tally marks and then drawing the histograms. At this point I also thought it advisable to talk about why bar charts have gaps between the bars and histograms do not. This discussion was also very interesting and quite a few contributed to it. By the end of it I felt that they had convinced each other of the reasons for it being so.
![]() Pause for thought Mrs Mohanty included a lot of whole class discussion during this activity. Can you think of any strategies that she might have used to include discussion in pairs or smaller groups during the main part of the activity? Now think about how the activity went with your class and reflect on the following questions:
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