What are the most likely reasons staff may need to work on a Friday under a 4-day school week?

Targeted assistance will be provided to students on Fridays in some cases. Teachers who volunteer for these assignments have the opportunity to earn money for the time worked. There are 2 federal holidays that fall on Mondays. For these weeks, students and staff will attend school on Friday. On the first week after Christmas Break, there will be a Monday PD day, and students and staff will attend school on Friday. Any regularly scheduled duties and job functions associated with extracurricular activities are still required on Fridays. There are two inclement weather make-up days on a Friday.