Jamie York's presentation which explains how each of the conic sections - ellipse, parabola, hyperbola - are generated by slicing a (mathematical) cone.
Maybe this professor didn't get the memo that the computers exist and that this can be visualized very easily. In fact one could find an existing video on yt depicting the animated conic sections.
Great hands on demonstration. Does his discussion of the slope of the cut correspond to the eccentricity of the conic section? I.e., clearly a horizontal cut (perpendicular to the axis of rotation of the cone) creates a circle with eccentricity 0, while a cut that is parallel to cone creates a parabola with eccentricity 1. Can ‘e’ be defined in general as a simple linear relationship concerning the slope of the cut or is it more complicated relationship for ellipses and hyperbolas?