To become a skilled sheet metal worker training is essential. It can be acquired informally through "learning-by-working;" through company on-the-job training programs; by attending trade or vocational/technical schools; through unilaterally (management or labor) sponsored trainee programs; through registered labor-management apprenticeship programs, or a combination of the above. It is generally accepted that the more formalized training programs give more comprehensive skill training. Recommended high school courses include English, general math, geometry, trigonometry, mechanical drawing, physics, and general science. Computer literacy is becoming more important as both layout and Computer Numeric Controlled Machinery (CNC) operation is facilitated by computers