PPT Demo

[mikestatic]

Last year I was shown a Vizard/PPT demo that had people cross over a pit by stepping on a a board. The demo used the classroom portrayed in some of the Vizard tutorials, but I cannot figure out how to select the single tile in the floor to open the pit. Is this demo available for download? If not, is there an easy way to replicate the demo using the files available in the tutorial? I'd love to use this demo as a means of demonstrating the realism evoked by the virtual world. I also find that the train station demo is especially good for this.
Thanks,
Mike