This paper presents an initiative that seeks to develop some skills of 3-D visualization by using the capabilities of programming and graphical representation of a computer algebra system, in this case Mathematica. A specific procedure has been developed to allow engineering students to represent the families of curves obtained by cutting the 3-D graph of a two-variable function with families of planes having different orientations. This initiative achieves an improvement over the use of the contour plots, shows a new point of view about the functions, which depend of an angle, and can be extended to be used with nonplanar surfaces.