Imagine that someone has invented a super-powerful microscope attached to a camera. With this microscope we can actually see electrons, but the "depth-of-field" of the microscope is so shallow that it can only focus in one plane, the xy plane i.e. with \(z = 0\), and only electrons appearing on, or very near this plane, are going to be seen. Every few milliseconds or so, a new exposure is made, but always on the same piece of film. If electron happens to be in the xy plane, its position is recorded as a dot on the film. As time passes, regions where most "sightings" are made will be thickly sprinkled with dots, while regions where the electron is not so likely to be seen remain dark. Eventually the brightness of a particular region indicates the probability that the electron will be found there. The diagram to the left of the window shows the results of this "experiment".
You can start to work on a new orbital whenever you like by making another choice. Initially, by default, a sighting will be recorded each time you click on the "Shutter" button. Clicking in the "Auto" box makes the program run automatically, marking sightings as quickly as the program can generate them. You can stop this any time you like by clicking on the "Shutter" button. Allow the diagrams to develop for several minutes until you are sure of their appearance.