We don’t have a school-wide celebration as such, though I think it is a good idea. We do have an opening chapel that involves all the students, staff, administration, and school board and their wives. This serves as a welcome back to school and a time for the principal to go over the whole school policies and make any announcements that may be necessary.
Then it is up to each teacher if they want to do anything special in the way of celebration. Often the day is spent doing less work but taking time to thoroughly introduce procedures and expectations. Last year the Jr. High teacher did several team-building exercises that her students enjoyed. It was a good way of mixing the new 7th graders with the 8th graders she’d had the year before. I like to take individual student pictures at some point during the day. I later use these pictures for birthday gifts, as a who’s who in the class by the door in hall, and for other things. Last year we finished up the day with popsicles.