I am currently at work on a project to put flashing lights on school zones for times when the speed limit is reduced. It has been noted that the practice of flashing lights is meant to increase visibility of the signs during the times they apply. The trouble is that the drivers start to rely on the flashing to tell them when the signs apply, and thus start to appeal on speeding tickets if the sign does not flash. It was assumed that drivers were conscientiously trying to obey the law and that the lights would make this easier. Instead the opposite has turned out to be the case. It's the law of unintended consequences. You try to draw attention to make school zones safer, but if the signs fail and drivers depend on them, they will be far less safe. It seems a no-tech solution is better from that point of view.
I think drivers should slow down in school zones by default, then check whether the regular speed limit applies. We think of the default in that zone as the higher speed, but it seems safer to me to assume that the lower speed applies until shown otherwise.
Mokalus of Borg
PS - If your counter-argument is "but that's really annoying", then you lose.
PPS - "Annoyed" is better than "I injured some children today".