This gets trotted out every year, it's mostly rubbish. As a school governor I can tell you now that all the schools I have contact with/have had contact with (10) keep going up to the last day with the core subjects.*
As a school governor in both secondary and primary, that’s what maybe happen in your school, however in the schools I am involved in, core subjects are definitely finished and it’s all fun and social activities.
Y5/6 are having a sporting game day and then this afternoon going to the pantomime
Tomorrow they have their Xmas movie and are having a toy day in the morning and in the afternoon it’s their Xmas party.
Thursday is a whole school assembly morning and afternoon and the kids are allowed to bring in treats, and the kitchen is making cookies and hot chocolate.
Friday they break early, they have a £1 SS gift to give out, and they are having a whole school mini disco.
At secondary it’s similar but more sport involvement and more social interaction with other year groups.