I was at first a bit worried of such demonstration held at school
I was kind of nervous, too, but we adapted quickly and focused on stuff that captured the attention of the age group. They were young enough (6-8th grade) that we could get their attention with some action. Don't try to just lecture.
We switched off speaking frequently, helped fill in, and took over when we started to stumble verbally. On the whole I think we worked together fairly well. No egos tried to upstage anybody else.
With highschool kids we may have had to use one or two for cutting demonstrations before we got their attention. That can be a rougher age group to work with.
Rob: If I had to guess, I'd say spring 1988, but I'm not 100% sure. I'd have to determine whether there was a winter without Lauralee. I do have photos from that demo (including you piping) in a box in the basement. If I run across them I can scan them. I'll send you a private message if I find them.