It would certainly be a fitting show of respect if they did lower it. But perhaps they simply overlooked it. It might be a nice thing for you to POLITELY speak to the principle or superintendent to discuss it.
Everyone that isn't in a private school attends school in a government facility. You attend school on government land in a government owned building, & are taught government dictated curriculum, in government published & approved books by government paid teachers. All the flags around here have been at half mast for days
While I see the respect given at putting the flag at half mast, the tragedy was on Monday. Is today the official day of mourning? If not then I'd rather see the flag flying high and proud to show that the terrorist, foreign or domestic, cannot keep this country down.