Mass. Gen. Laws ch. 112 § 241
An apprentice, before starting an apprenticeship, shall file an application with the board, accompanied by the appropriate fee, requesting that an apprentice license be issued. The application shall be made on a form to be furnished by the board and shall require the applicant to state his age, the employers name and address and such other information as the board may require. A master sheet metal worker may employ more than 1 apprentices but not more than 1 apprentice may work under the direct supervision of a master or a journeyperson in the employ of the master. The board may, by regulation, establish a maximum length of time for apprentice training.
Notwithstanding this section, students in a vocational school accredited by the department of education, under the direct personal supervision of a master or journeyperson sheet metal worker who is certified as an instructor by the division of occupational education, may engage in an on-the-job training program on installations approved by the examiners and conducted in cooperation with such a vocational school. The examiners shall adopt rules and regulations relative to the on-the-job training program and may accept such training as fulfillment, in whole or in part, of the necessary prerequisites for journeyperson licensure.
Mass. Gen. Laws ch. 112, § 241