The Challenge: Percentages of the Whole
Circle graphs require students to understand how the parts of the graph make up a whole. For example, a cereal may contain eight different ingredients in differing percentages. Each ingredient is one of the sectors of the circle graph, with all eight of the ingredients equaling 100 percent of the cereal. All the ingredients must be accounted for by the graph, since a circle graph, by definition, represents 100 percent.
The ability to analyze information in different parts or sectors and then to synthesize the information as a whole is an integral part of interpreting circle graphs in the areas of social studies, science, and math. Students need practice in identifying real-world examples of how circle graphs are used to display information.