Mass. Gen. Laws ch. 149 § 74
Except as provided in section fifty-six, every person employing any minor in any establishment mentioned in section sixty shall keep posted in a conspicuous place in the room where such minor is employed or permitted to work a printed notice stating the number of hours such minor is required or permitted to work on each day of the week, with the total for the week, the hours of commencing and stopping work, and the hours when the time allowed for meals begins and ends for each day of the week.
The employment of any minor at any time other than as stated in said printed notice shall be deemed a violation of this section. The terms of such notice for any week or part thereof shall not be changed after the beginning of labor on the first day of the week without the written consent of the attorney general.
Mass. Gen. Laws ch. 149, § 74