should've known better

Two teachers are in trouble after vandalizing a new sidewalk.  The Vermont teachers drew on a wet cement sidewalk hoping that the drawing would stimulate their special needs students while on their walks.  But the city didn't see any educational value in what they say was a drawing of a rat with the initials "J.R."  The teachers claim that it was supposed to be a dinosaur.  They've already written letters of apology to the city and will be required to do community service along with paying a fine.  teachers