Reading the Bars: Making Sense of Bar Charts

Imagine your class votes for their favourite fruit. Ten children choose apples, six choose bananas, and four choose grapes. How would you show this information so anyone could understand it quickly? Think about it for a moment. A picture made of bars could do the job perfectly — and that is exactly what a bar chart is!

A bar chart is a diagram that uses rectangles — called bars — to show amounts. Each bar stands for one category, which means one group or type of thing. The taller the bar, the bigger the amount. Every bar chart has two axes. An axis is a straight line along the edge of the chart. The horizontal axis (going left to right) shows the categories — for example, the names of fruits. The vertical axis (going up) shows the scale — the numbers that tell you how many. The scale goes up in equal steps. If the steps are 2, 4, 6, 8 then each jump is worth 2. Always check what each step is worth before you read a bar. To find the value of a bar, look across from the top of the bar to the number on the vertical axis. That number is the value — how many things are in that category. Worked Example: Look at the bar chart for favourite fruit. The bar for Apples reaches up to 10 on the scale. The bar for Bananas reaches up to 6. The bar for Grapes reaches up to 4. • Which fruit is most popular? Apples — because its bar is tallest (10). • Which fruit is least popular? Grapes — because its bar is shortest (4). • How many children chose Apples or Bananas altogether? 10 + 6 = 16 children.