Re: Halloween,christmas,valentine
It’s interesting. I teach at a Jewish school, and there is no acknowledgement of Halloween. We are asked strictly not to condone or celebrate the holiday, as there is a history of Jewish persecution associated with it. Despite that policy, most of the kids go out trick-or-treating and such. I’ve even had many argue that I’m not allowed to give homework that night. 
(One argument was even that it is a national holiday ← this was from an international student 
)
However, we are certainly allowed to share and mark our own religious holidays and tell the kids about them.