Given a function of two variables f(x,y) and a domain point (x0,y0), this worksheet provides a plotting tool that can be used to plot the function f(x,y) superimposed on a plot of the line that is tangent to the graphed surface at the point (x0,y0,f(x0,y0)) and lies in a vertically oriented cutting plane determined by the direction in which the directional derivative is desired. The gradient vector is plotted in a plane parallel to the xy-coordinate plane along with a vector representing the direction associated with the directional derivative. The user has a choice of generating a single rotatable 3D plot or an animation consisting of multiple plots that show the effects of progressively changing the directions associated with the directional derivative.