A much better introduction to the commandline is Neal Stephenson's "In the Beginning was the Command Line."
Read it here: http://www.cryptonomicon.com/beginning.html
Did you have a live terminal on the projector and demonstrate a few commands and then show how the output of one can be piped into another?
I'm interested in the balance between demo and explanation for this kind of audience.
A much better introduction to the commandline is Neal Stephenson's "In the Beginning was the Command Line."
Read it here: http://www.cryptonomicon.com/beginning.html