Our approach is centered around the concepts of "state" and "orbital". Its primary aim is to explain and calculate phenomena and basic facts like size, spectra and energies of different atoms, molecules and solids. Our approach makes use of the analogy with standing waves and uses model building with the computer (STELLA) to avoid high mathematical difficulties.
Finally we give very short results of a case study of one student following this course. We show four different states of his learning pathway to a model of the atom, starting with a planetary model and coming to a model of a distributed electron cloud. A short characterization of his final cognitive state follows.