Plumbing involves installation and repair of a wide variety of piping systems and equipment. The majority of plumbing work is in the commercial segment of building construction. From layout (or design) preparation to the final installation of fixtures and equipment a PLUMBER practices daily all the mental and physical skills acquired through a structured learning process. The layout and installation of piping materials, plumbing fixtures and mechanical equipment are learned on the job. Blueprint reading, drawing, trade math, related systems, theory and selected manipulative skills are taught in the related school program.