## Lesson: Finding the Length of a Line

Developing the Concept

**Materials:** poster paper or a transparency and overhead projector for demonstration; straightedge; Coordinate Grid (PDF file) Worksheet or Learning Tool 51 in the *Learning Tools Folder,* and a straightedge for each student

**Preparation:** Draw a coordinate grid on poster paper or a transparency. Label the *x-* and *y-* axes from 0 through 10. Make copies of the grid for students.

**Prerequisite Skills and Concepts:** Students should know about ordered pairs and locating points on a grid. They should also be able to recognize and interpret an equation.

**Wrap-Up and Assessment Hints**

Reinforce the idea that these techniques only work on horizontal and vertical lines. As you assess students, make sure they are using the correct coordinates for each kind of line. One way to provide some additional help for students having difficulty is to use inch-ruled grid paper and provide students with rulers. Let them measure the line segments with the ruler and compare the results to the answer they get.