I worked at an elementary school where I taught photography to a group of kids ranging from 3rd grade to 7th grade. I have some materials that I have filed away somewhere that I'll try and find to pass on to you.
I can tell you one thing, don't be afraid to throw information at them, explain a concept, give an example and then review it the next day, they'll pick it up! My kids fully understood the relationship that aperture, shutter speed, and ISO within about 2 days!
I guess the other thing that I thought was great when teaching kids photography, was don't focus too much on "be very careful, this camera is expensive and not a toy" type thinking. Don't baby the camera you give kids, just teach them to be responsible with it and to use the strap. I taught my kids for example, if you're going to be handing the camera to someone have them grab the camera, then while they're holding it, you take the strap and put it around their neck. that way someone is always supporting it. With the kids doing that, I only had 1 camera fall out of 20 or so students over a few month timespan.
Some cameras, some lenses, plenty of gaffer's tape and beer.