Abstract: A set of tiles for covering a surface is composed of two types of tile. Each type is basically quadrilateral in shape and the respective shapes are such that if a multiplicity of tiles are juxtaposed in a matching configuration, which may be prescribed by matching markings or shapings, the pattern which they form is necessarily non-repetitive, giving a considerable esthetic appeal to the eye. The tiles of the invention may be used to form an instructive game or as a visually attractive floor or wall covering or the like.