How I Would Teach Bar Charts In Year 4
By Shannen Doherty
Years ago, when working as a Year 4 teacher and aspiring Maths Lead in a small primary school in Croydon, our staff were split into two groups (KS1 and KS2) for lesson study in Maths. This meant the headteacher took the whole school into the hall while the teachers worked in a group to collaboratively plan a short sequence of lessons for one class that we would take turns teaching. We chose the KS2 (Year 4 in the National Curriculum) objective “interpret and present discrete and continuous data using appropriate graphical methods, including bar charts and time graphs”. So, while there have been some changes to the way in which I’d approach it now, I must absolutely give credit to Sally Dubben and Nicola Robinson as this was a group effort!
It’s important to say that when teaching this series of statistics lessons, the children should be confident reading number lines and working with numbers. If they aren’t, then I’d recommend some pre-teaching on this before beginning.
Before starting this lesson, briefly review prior knowledge and vocabulary e.g. bar chart, x-axis, y-axis, data, table. They will have spent some time on pictograms and simple bar charts in Year 2 and Year 3, so will have some knowledge already.
First, you need a selection of bar charts. A wide range of bar charts is needed, so aim for:
- Vertical bars
- Horizontal bars
- Bars of differing thicknesses
- Intervals of one, two, five and ten
- Discrete data (bars not touching)
- Continuous data (bars touching)
- Bars of the same colour
- Bars without colour
- Different coloured bars
When you have your bar charts (I think I ended up with 17 when I did this last!), give them to the children in pairs and ask them to sort the bar charts. The beauty of this task is that there is no one right answer, so there is no pressure to be correct. You will get a number of categories being suggested, such as thin bars, thick bars, coloured bars, touching bars, and non-touching bars, and you might even get some who notice the differing intervals. This conversation is a nice way to discuss what is and isn’t important when presenting data on a bar chart.
Once everyone has shared their ideas, ask them to put their bar charts into two groups: touching and non-touching bars. Ask them to look for what is the same and what is different about these two piles of bar charts. This is where we teach the concept of discrete data and continuous data. For anyone who isn’t sure, discrete data is what can be counted and can only take certain values e.g. the number of students in a class, the number of fruit sold at a market, or the number of times a die lands on two. Continuous data can take any value within a range and can be measured e.g. a person’s height, the mass of an object, and the distance someone jumps.
When presenting discrete data on a bar chart, the bars should not touch, and when presenting continuous data, the bars should touch. Now they know the idea of discrete and continuous, put some bar charts on the board or under the visualiser and ask them if it shows discrete or continuous data. As a challenge, put a table of data up and ask the same thing.
Here I would give the class a short task including questions on identifying discrete or continuous, matching tables to bar charts and finding mistakes on bar charts showing discrete and continuous data.
Next, show the class two graphs side by side that show the same data, but with different intervals, for example, show the results of a class vote on their favourite fruit on two graphs, one with intervals of one and one with intervals of two. Ask them what they notice and what is the same and what is different. Explain that we can represent the same data, but that the intervals on the axis can make the data look different.
Go back to the original stack of bar charts and ask them to sort them based on the intervals. Ask them why some bar charts might have different intervals. Explain that it all comes back to the data at hand and how high the values go. If we’re working with values between zero and 20, then intervals of one or two should suffice. If we’re looking at values up to 200, then we’ll probably want intervals of 10.
‘Zoom in’ to the y-axis of one of the bar charts that have intervals of one and ask the children to find different values on it. Then, do the same with intervals of two, five and ten to ensure that they remember how to read the scale on each bar chart going forward. Give them some independent questions on vertical and horizontal number lines to read and find values using different scales.
Now we’ve looked at discrete and continuous data, and how intervals on an axis can vary, it’s time to look at a bar chart in more depth. Show them a bar chart and model how to 1) look at the title and axis labels to understand the context of the data, 2) look at the intervals to understand what numbers we are working with and what each gap is worth, and 3) use your finger to trace the axes and bars to ‘read’ the data on the bar chart. Then, show another similar bar chart and have them do the same in their pairs.
Ask them questions such as “How many children voted for pears?” so they can retrieve data quickly from the bar chart. Model how to answer the question and then give them a bar chart on paper with some questions to practise this independently.
Then, move on to questions such as “How many more children voted for apples than cherries?” or “How many votes did bananas and peaches get all together?” or “How many children voted altogether?”. Model answering these questions using ‘I do, we do, you do’ until they are independently interpreting bar charts.
After this, you can move on to presenting data on bar charts and then looking at time graphs, but that’s another article altogether!
You can read more articles by Shannen Doherty here.