To my knowledge, whenever Secret Service agents are actively safeguarding the lives of persons assigned to, they are armed. Those assigned to guard the President's daughters at Sidwell Friends are armed. So while Sidwell may not have armed guards, armed guards are present when the offspring of a President attend any scholl.
The point is: Are the polititians in DC sending their kids to a school that employs armed guards? The NRA said their ad was not about the USSS.
The WAPO gives the NRA 4 Pinocchios, but then the question of whether Sidwell employs or contracts for armed guards is not answered.
Is this typical liberal hypocrisy? Armed guards for them, gun free zones for all other kids.