## Lesson: Making a Double Bar Graph

Introducing the Concept

Your students have made and interpreted bar graphs before, but this lesson is probably their first encounter with double bar graphs. Start out by asking students what bar graphs are and where they have seen them before. Guide students to discuss the ideas that bar graphs show information with bars or rectangles, that longer or taller bars show greater numbers than short ones do, and that bar graphs may be in horizontal or vertical formats. To generate interest in the topic, help students generate and organize some data about themselves.

**Materials:** chart paper, chalkboard or writing board; small squares of paper or self-adhesive notes in two colors

**Preparation:** none

**Prerequisite Skills and Concepts:** Students should be familiar with bar graphs for showing data. They should know that graphs have descriptive titles and that their axes are labeled. They should be able to read from the end of a bar to its number on an axis to determine the number that is being shown.