The document describes the Cartesian plane, which consists of two perpendicular number lines that intersect at an origin point. Each point on the plane can be named with two numbers (x, y) which are its coordinates. The x value represents the horizontal distance from the y-axis, and the y value represents the vertical distance from the x-axis. Some example points are given as (x,y) coordinate pairs. Linear functions of the form f(x)=mx are described, where m is the slope. If m>0 the line is increasing, if m<0 the line is decreasing. Examples of determining if functions are linear and graphing a linear function f(x)=2x are shown.