About This Lesson
This lesson takes students from recognizing that the proportional sides of similar triangles can be used to determine a ratio describing the steepness of a line, slope, to the derivation of the slope-intercept form of a linear equation passing through any point on the y-axis. The lesson is in three parts. Each part must be done in order for students to attain the conceptual understanding that slope is unique for each line and is integral to the equation of a line.