Prior to the start of the school year, he had the faculty give him the names of all the drug dealers, gang bangers and major miscreants.
The first day of school he had an all-school assembly and called this relatively small handful of jerks to the stage as though they were going to receive some sort of honor or special recognition. He then called some uniformed security guards to surround them and told the assembled student body to take a good look at them because they wouldn't be attending school there anymore.
As the guards escorted them off the stage and out the door, everyone else applauded. I realize it was only a movie (though it was based on a true story), but the looks on the hoodlum's faces were priceless!
What a great movie.