I had an old boss get nabbed for something like that in a Lambo he'd just bought. He was such a d-bag, he disputed, hired a lawyer, stretched the whole process out for a long long time, managed to seriously worry the judge that he was never going to stop making arguments, and finally, the last straw was the lawyer asking the officer how he knew for certain that it was a school day and the school zone was in effect. When the officer hesitated the judge tossed it out with some scathing remarks aimed at my ex-boss and his lawyer for wasting time/money in such a way.
Needless to say, if you're going excessive speeds in a school zone, you're probably not a straight-up kind of person. :P