What is a Bar Chart?

A bar chart (or graph) organises information into a visual representation using bars of different lengths. The length of these bars is proportional to the size of the information they represent. For example,

Class 3A went outside of their school at 10am for 45minutes to see what types of vehicles passed their school in that time frame. Here is a table showing their results.

Types of Vehicles	Total AM
Cars	25
Vans	15
Lorries	12
Motorbikes	10
Bicycle	5

Now that the children have this data, they need to assess what to do with it to show visually what trends the traffic had. As we can see here the average total is a multiple of five. This means that our scale along the vertical axis of our graph would be better suited to increase by fives. We can see that lorries are the only vehicle that does not follow the average and so the bar that would be used for this vehicle would stop halfway between the two sections. Let me show you what that means.

 

Here we can see that by increasing the vertical axis scale by fie we are able to keep the graph smaller. If we went up in two’s or one’s the graph would be too large to fit on the child’s page (or might need one page just for it and nothing else!)

 

 

To read a bar chart, consider the length of the bar connected to each category to find its value. If the bar does not line up with a number, but falls in a gap, the value would be the number that falls in between the two numbers given.

 

What are the different types of bar charts?

There are a few different ways in which bar charts can be used depending on their purpose. Let’s look at each of these in more detail.

 

Horizontal/Vertical bar charts:

The bar chart shown in the previous section is an example of a vertical bar chart. A horizontal bar chart presents information in a similar way, but with the bars going in a horizontal (side to side) direction instead of vertical (up and down). Whether you decide to lay a graph out horizontally or vertically is a stylistic choice.