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Convenient reflective diffraction gratings in physics teaching

Students often have difficulties comprehending situations in which wave characteristics of light are manifested. After teaching wave optics, we studied the level of understanding of reflective diffraction of light with a group of secondary school students, and the phenomenon of diffraction in general. We analysed the possibility of using convenient reflexive diffraction gratings (compact discs and rulers with millimetre and half-millimetre markings) using suitable research school experiments which can be prepared. With appropriate methods of visualising the superposition of light waves, those experiments represent the basis for an appropriate conceptual change in the understanding the diffraction of light.