Students at a high school in Cantley, Doncaster have been banned from wearing traditional ties in favor of clip-ons because officials fear that students might strangle themselves. Seems to us that if tying a tie is so complicated to your students that they're strangling themselves, you should probably be pumping more money into the education system, not catering to their stupidity.
Clip-on ties can be quite dangerous in the wrong hands (i.e. your students). For example, say they're running around and one kid grabs the other by the tie, the next thing you know, the tie comes off and it ends up down the kid's throat. He's choking, isn't getting oxygen to the brain, and BAM!, he's dead.
Perhaps you should print ties on the school-mandated shirts. That way, the illusion of wearing a tie is still there, but with none of the dangers. And you should make them wear helmets too, just because you never know when one of them will turn a corner too fast and fall down.