Reading through others' comments, I remembered:
- In NYC at least, there's a city-wide censorware blacklist run by the Board of Ed. If that's the case where you are, find a way to bypass it, immediately. There were constant mishaps. For example, one teacher had a curriculum based around students' use of Goodreads. One day early in the term, goodreads.com got blacklisted as a social networking site. Many phone calls to the censors were needed.

- It's much easier to troubleshoot issues if the students all use one login - "student" works well.

- Students shouldn't be able to save files to their local desktop. That said, sometimes the network will be down and they need a way to save their work. Flash drives aren't an option in that environment.

- Having a way to update to the most recent version of Flash is often a surprisingly necessary thing to do. Most of the content at www.pbs.org, for instance, is Flash-based.

I worked for a program that brought computers into inner-city schools in NYC. I was responsible for overseeing two computer labs that received after-school use, and a dozen laptops that went in a rolling media cart. The laptops were running Edubuntu. I was on a six-month contract and so I don't have as many answers as I'd like, but here's a few lessons learned.

MOST IMPORTANT:
- You can't give the school computers, particularly running Linux, and walk off - even if the teachers are tech-savvy (most will not be). Your project will die off quickly if you don't make a long-term commitment to support it.

Edubuntu-specific:
- Linux support for wireless drivers is less than perfect. Skip wireless, or test thoroughly. Flaky wireless gave our Edubuntu project a poor reputation very quickly.
- Also test the printer drivers.
- Many schools have inane requirements that you'll need to support. For instance, our program required that the students be tested using software from Scholastic that was Windows-only and made of fail. The school neglected to tell us that this was a requirement at the time we decided to go with Edubuntu. We also weren't told that they'd want them for a comics-making course - there's no comic-making software for Linux.

More generically:
- Everything not nailed down will walk off. Not just mice and power cables, but even stupid things like monitor-to-PC VGA cables walk. Make laptops get checked in and out. The cables connecting peripherals to desktops should be inaccessible to users.
- 3 out of your 4 non-ruggedized laptops will need replacing after a year.