will go into effect. Nothing in this subsection shall be construed to prohibit an employer from providing greater advance notice of a retail, food service, cleaning, or Secretary's designated employee's work schedule than is required under this section. (3) Work schedule changes made with less than 24 hours’ notice An employer may make work schedule changes as needed, including by offering additional hours of work to retail, food service, cleaning, or Secretary's designated employees beyond those previously scheduled, but an employer shall be required to provide one extra hour of pay at the employee's regular rate for each shift that is changed with less than 24 hours’ notice, except in the case of the need to schedule the employee due to the unforeseen unavailability of a retail, food service, cleaning, or Secretary's designated employee previously scheduled to work that shift. (4) Notifications in writing The notifications required under paragraphs (1) and (2) shall be made to the employee involved in writing. Nothing in this subsection shall be construed as prohibiting an employer from using any additional means of notifying a retail, food service, cleaning, or Secretary's designated employee of the work schedule of the employee involved. (5) Schedule posting requirement Every employer employing any retail, food service, cleaning, or Secretary's designated employee, subject to this Act shall post the schedule and keep it posted in a conspicuous place in every establishment where such employee is employed so as to permit the employee involved to observe readily a copy. Availability of that schedule by electronic means accessible by all retail, food service, cleaning, or Secretary's designated employees, of that employer shall be considered compliance with this subsection. (6) Employee shift trading Nothing in this subsection shall be construed to prevent an employer from allowing a retail, food service, cleaning, or Secretary's designated employee to work in place of another employee who has been scheduled to