The advanced theoretical and empirical models of strong ground earthquake motion are built on assumptions about the nature of strong ground motion that are drawn from elementary and direct studies of recorded strong ground motion. This brief note reviews selected published elementary studies, emphasizing their significance for the subsequent advanced studies, such as detailed regression models for peak amplitudes and esponse and Fourier spectra of strong motion. The illustrations are mostly from published work by Strong Motion Group at University of Southern California. They contributed many such elementary studies and have later used their findings in development of advanced regression models. Specifically, this note reviews observations on: the spatial attenuation of strong motion, the interpretation of its wave content, small versus large amplitudes, the strong motion magnitude scale, and the principles of empirical scaling of strong motion for use in earthquake engineering. It also presents selected examples of how the observational evidence, as recorded on accelerograms, has contributed towards creation of new and refinement of the existing theories.