Using Similar Triangles to Understand Steepness of a Line
In this lesson, students will apply what they know about similarity and use repeated reasoning to recognize that the ratio of vertical length to horizontal length of similar right triangles is constant. This sets the stage for defining the numeric measure for the steepness (or amount of slant) of a line, called the slope of the line. Students who are ready to take it further will investigate the measure of steepness for vertical and horizontal lines.