They did yesterday, though: two knuckleheaded kids in the Grade 10 class I was teaching, four minutes in, decided it'd be a good idea (after one called the other a name) to leap up from their desks and grab each other's shirt as to suggest that, given a little more time, they'd get to throwing punches. (You know how when hockey players get into a little, as the commentator might call it, "a little pushing-and-shoving around the crease"? It was a little like that.)
All in all, though, it's been a fairly uneventful start to the school year. Things are progressing, best as I can tell... but you really can't gauge how a class is going to go until at least the second or third week. Right now everyone's a little tentative, seeing how things might go, seeing what everyone else is about, and trying to figure out who I am. Standard stuff.
In conclusion, to quote The Who, "the kids are alright."