How does canceling classes stop the threat, do you people really think that a crazy person would have the date locked in stone? If someone was really planning something then yes, they messed his plan for the 16th up but, what's to stop him from moving his plan to today, or next week, or next month? Now folks are going back to classes today thinking they are perfectly safe because it is not the 16th anymore. The date has been made out to be the most significant part of the threat by the local media but, I argue that the date is the most insignificant part of the threat. This person could do something at anytime but, people will now let there guard down because it's not the 16th.
Also, what if the actual intent was to get classes canceled on that specific day for some reason, then the person's plan actually succeeded.
I don't know what the answer is, you can't cancel classes everyday but, I'm also not naive enough to think that the threat can now just be tossed aside because it is the 17th. Unfortunately many people will do just that; it's the 17th, we are safe now.