This lesson is optional because it provides students with additional opportunities to practice drawing and describing lines and calculating the slope of lines given two points.

Students begin the lesson by observing two graphs and describing the similarities and differences between them. Students are encouraged to use precise language to describe characteristics of each graph, such as using slope and vertical and horizontal intercepts (MP6).

Next, students use the Info Gap structure to describe a collection of lines while their partner attempts to recreate the design. Students find there are many methods for describing the location of lines, but the focus in this lesson is on using slope and the coordinates of a point on the line.

Last, students recognize the importance of performing calculations in a consistent order when finding the horizontal or vertical change between a pair of coordinate points.