Silhouette of a hand made by spraying a sheet of paper with sensitive liquid development; then exposing the light-sensitive paper with your hand to mask an area that remains in shadow; while the illuminated part becomes black. Exposure to the finished paper sheet is passed in the fixing bath; making stably white the part not exposed: the imprint of the hand camera. Experimental teaching demonstration for the formation of photographic images on photosensitive support as we are used to seeing it; it's just one of the possible applications of the photographic technique. The photograph has been teaching the driving force for the formation of the group photos / gram; co-founded by Ando Gilardi and a complex of investigators composed of teachers and students; who since 1979 has played at many Italian schools innovative courses; publishing three manuals to use of teachers. Milan; 1985