Our school does the same, putting the Friday before and Monday after Easter into the school calendar as make-up days for bad weather. If we don't use the bad weather days (which we didn't this year), then students and teachers are off on Friday and Monday. Actually next year there is a move to place one of the bad weather days on another Friday rather than the Monday after Easter. Unlike your area, the town where I work, even though much like the rest of East Texas, has a fairly strong Catholic history/presence as well. Add to that the high portion of Hispanics who have moved here that are of the Roman Catholic tradition, our school takes a pretty hard hit on the Average Daily Attendance when they have classes on Good Friday.
Cultural holidays provide a nice break, whether or not they are scriptural.