Broken Window Theory

Have you heard of "Broken Window Theory"?

According to the theory, when a broken window is left un-repaired, it sends the message that nobody cares about the broken widnow. Pretty soon more windows will be broken, there will be graffiti all over the place and neighborhood will quickly turn itself to a ghetto.

I guess this theory can be applied in may different ways, such as one student looking at porn during class.