Bars and Pies

Maps like the ones on the previous page are are not the only way to show changes over time. Charts can be especially useful for showing information that applies to several different groups or different time periods. For instance, take a look at this bar chart. What two things are the bars used to compare?

For each day there are two bars--a green bar for a jar left in the sun and a blue bar for a jar left in the shade. By looking at the height of the bars, we can see how much hotter the jars in the sun were than those in the shade.

Another visual element that helps readers compare facts is a pie chart. The "slices" in a pie chart show parts or percentages of a larger number. The pie chart on this page shows the results of a survey meant to identify people's favorite fruit--using a different "slice" to show how popular each fruit is. When you look at this chart, you see that apples were by far the favorite fruit of the people who took the survey.