Chapter 4 is the most important of this learning software. It allows you to improve and test your diagnostic skills by solving diagnostic exercises using a virtual microscope. However, for several reasons, these exercises cannot replace working with a real microscope: the maintenance and handling of a real microscope cannot be simulated! In addition there is an important limitation since only a two-dimensional picture can be screened. It is not always possible to see all characteristic criteria, e.g. the number of nuclei in an amoeba, in one plane. For convenience you can zoom the picture with the bar on the right-hand side. With a real microscope you do not have this feature and you have to select the magnification by choosing appropriate eyepieces and lenses.