Hello,
I apologise for duplicating this post from the Leopard threads, but it's quite short! I suggest using this as a pedagogical opportunity.
Turn on VoiceOver on one machine and blindfold a volunteer. This is more dramatic and will have a bigger impact than simply activating the screen curtain. Explain to the kids the use of VoiceOver and guide your volunteer through a simple task such as creating a postcard home in TextEdit.
When they realise just how useful VO is, and at the same time how difficult it is to navigate a machine when you can't see the screen, you should have no more discipline problems. I think all you'll be left with is a sense of awe among the kids that such a thing is possible.
And if you really want to shock them, try playing them some of the videos from the
AssistiveWare site. I'd suggest using Anne's to give a short intro to the use of VoiceOver professionally, and then Marie-France's, showing just what an effect VO can have. As a tip on the latter, translate the message Marie-France types to her mother: "Maman, peux-tu mettre ma tête droite?" (Mum, can you straighten my head for me?). I'm certain the sheer punch of this simple message from someone so helpless as to be unable to put her own head in a comfortable position will put an end to any cynicism or amusement. Since most kids carry an iPod or similar device with them, you could then get them to plug the earbuds into their machines and try the basic steps for themselves—without interfering with each other.
Finally, I'd also suggest that you post up a list of the shortcuts to turn on and off the various Universal Access facilities, with a brief explanation of the role and function of each.
HTH
Archie