Have you looked into the CyberPatriot program? http://www.uscyberpatriot.org/Pages/default.aspx It's a "secure the platform" high school competition that focuses on defense instead of offense. It's all set up and ready for schools to get involved.
For training, they provide virtual machine images that students can learn on and practice securing. The installations are full of known exploitable flaws, with default passwords, open ports, inappropriate ACLs, guest accounts, extra services, unpatched web servers, all that kind of stuff. Offense takes place from a black box service that attempts to exploit the system, and provides a score to tell you that you secured 15 out of 80 known holes (or whatever).
For the contest, they provide encrypted virtual machine images that you download in advance. At the start of the contest, the teams are given the decryption keys, and then have a set amount of time to secure as many problems as they can find before the scoring agent is set upon them. The different stages of the contest have increasingly difficult tasks: round one might be to secure a Windows XP box, the next to secure a Windows 2008 server, and the final might be to secure a Linux/Windows network consisting of three servers. The competition is nationwide, with the final qualifying teams getting to travel to the national competition.
The black box attacker approach puts the emphasis on defense, and keeps the contest focused on practical application of the knowledge, rather than being a training ground for hacking. You still need to know what a SQL injection attack is, and how it works, but you don't have to practice them, and your team gets no points for being good at them.
It's already over for the 2012-2013 school year, but you can preregister a team or a school for next year.