First off, I'd kill to have my kids for 90 minutes daily, I hope that you'll come around to that idea too! Secondly, what are they expected to do? Do they help you run the building for events? Is your space rented out frequently or is it just the annual concerts and shows put on by the school. I'd look at this from a perspective of what do the kids need to know to make them work more efficiently as a crew.
We start out teaching basic
safety and rules for the space. Then we branch off into the different disciplines (lights, sound, carpentry, rigging,
etc). For most of our events I need kids that can program lights and patch mics and run a
mixer. If I don't have enough that can do that, I'm scrambling to run our rental shows.
An example of how I approach teaching them would be when we were going over lighting on Friday. I set up a pipe to practice hanging and focusing fixtures and they asked if they could patch in two lights on one
circuit. I then
led them through the process of figuring out if 2.4k dimmers could handle the load,
etc. Some got it right away and others were blank-faced. I then said, 90% of the time, I will be doing the math on the
plot and figuring out what loads can work. I need you to be able to run the board, hang and focus where I tell you to. If you plan on doing this after HS, even if you're just doing amatuer
theatre, you probably want to know about load balancing and more about electrical theory, but if not- no worries.
I always give them as much info as they want, but make sure they know what they need to know to work and operate in this building. I really try to make it like OTJ training as much as possible, so a lot of what you'll want them to know will be based on what do they
need to know to make your job functional and easier.
Here's another fun video I like to show kids-
http://www.controlbooth.com/threads/a-little-history-video.30398/#post-269735