Crystallography is a fascinating subject and an argument of great importance in the study of structure of matter and fundamental physics. Moreover, many characteristics of crystals, as well as other organic and inorganic substances, are analyzed with x-ray diffraction. In order to introduce at a basic level the above mentioned subjects, and also interference and diffraction of wave light, here we present some simple and new inexpensive optical experiments, analogous to the Laue diffraction of x-rays and electrons. We also propose an elementary geometric model to explain the two-dimensional pattern of diffractions by grating.