A: Invite them to join you in a secret society, making clear up front that the goal of the society will be the overthrow of the schools current administration and they will have to do a few things that are not technically legal but are harmless.
Start out small by having them repaint the principal's parking every day, making it slightly smaller each time, until his car no longer fits in his space. Then have them do the same thing with his pants.
Once they've grown accustomed to seeing the school's administration as a target for practical jokes rather than an authority, assign them a new task. Tell them you need them to lure the principal into a seedy motel, seduce him into wild night of cocaine-fueled bondage and videotape the whole thing. Remind them of the importance of secrecy.
If they carry out the assignment, without speaking a word to anyone, and deliver the videotape to your desk by Monday morning, they have developed responsibility.
And you will finally get that raise.