I know this is more of a pre-K cartoon, but I'm sure it will make many folks laugh in your staff lounge.
From the 9.28.09 New Yorker.
Funny, but a sad reminder of the eerie parallels between school and prison. For a full discussion of the story of how school and prison design evolved together check out Focualt's mind bending study Discipline & Punish: The Birth of the Prison.