In this lesson, students are introduced to the term vertical intercept, or -intercept, as the point where the graph of the linear relationship touches the vertical or -axis

Students begin by examining a graph that shows the relationship between the total number of pages read and the number of days, in preparation to identify a common error when graphing linear relationships. By noticing that the values for initial number of pages read and pages read per day have been swapped in the graph, students are shown how the -intercept and slope influence the shape and location of a line: the -intercept indicates where the line meets the -axis, while the slope determines how steep the line is.

Next, students match situations to graphs and then interpret the slope and vertical intercept in terms of the situation (MP2).