NOTE: This image provides only descriptions. If you click anywhere on this image, nothing will happen. Move to the real applet for action.

This is what you might see after you had entered a quadratic function into the z1(x,y) field of SurfacePlotter and a constant into the z2(x,y) field, and selected the options of revealing the "ticks" and "Hidden Surface Elimination" :

OK, I understand this. Let's move on to the next stop on the tour

No, I need to go back to the previous stop.