Distributing the literature is the hardest part about it.
http://www.megaphoneusa.com/CM-25 megaphone
25 watts, 1000 yards range, pistol-grip talk switch, siren alarm switch, microphone with coil cord, 8 C-batteries included, volume control, bell diameter 9", length 13", weight 4 lbs, and with shoulder strap.
1K yards > 1/2 mile
Assuming you have the balls, the time, and the transportation, from anywhere within a 3.14 million square yard area (thanks, basic geometry), you can communicate anything you want to the kids, violent or not. I strongly recommend getting closer than the full 1000 yards, do it at 500 and maybe penetrate some walls.