Most public school teachers are clueless when it comes to technology. At best, half of the math and science teachers will be technically savvy, while less than 25% of the English and social studies teachers will know the difference between a browser and a word processor. At the elementary level, you're talking 10%, tops.

It's the whole "teach a man to fish" thing. Having a single teacher on staff that is technically savvy breeds dependence on that one teacher and continued naïveté. If all teachers on staff except for a handful are clueful, the others feel obligated to catch up out of peer pressure.

The fact that you're installing Edubuntu is great, but teachers will go to the one technological in-service they get per year and wonder where the "Start" menu is when they get back to their school and sit down in front of one of your machines.

I'm a former high school teacher. Teachers are under exceptional amounts of stress in a classroom. You're performing in front of an audience for several hours every day. Anything that they're even slightly uncomfortable with will be left behind in favor of the familiar. You can either give up or you can work to breed familiarity.

I'd say keep up building machines, but also volunteer to offer in-service or after-hours training. You might not have to do it alone — you could probably get one of the clueful teachers at the school to teach sessions during the day or after school. But I promise, if you build machines and don't provide any kind of support for how to use them, they'll only gather dust.