Section 65. No person shall employ a minor under sixteen, or permit him to work, in any occupation for which a permit for employment is required, for more than six days in any one week, or more than forty-eight hours in any one week, or more than eight hours in any one day, or, except as provided in section sixty-nine, before half past six o’clock in the morning, or after seven o’clock in the evening, except from July first through Labor Day, when evening hours shall be extended to nine o’clock in the evening. If the work performed by any such minor in a day is not continuous, but is divided into two or more periods, the person employing such minor shall so arrange such minor’s work that all such periods of work shall fall within a period of nine consecutive hours. The time spent by such a minor in a continuation school or course of instruction as required by section twenty-two of chapter seventy-one shall be reckoned as a part of the time he is permitted to work.