To become a skilled glazier 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 general mathematics, blueprint reading, and general shop.