IMHO I don't see a problem; it's a speed limit sign and looks to be pretty clear on the side of the road; you were speeding, you got caught; you just gotta deal with it...
I don't think you have a snowballs chance in hell getting out of this given the fact a child was just killed on front of a school....
are you really pissed because you honestly feel the zone is not safe for children, or because you got a ticket?