prevent hard drive access from custom knoppix cd

Hello,

Is there a prefered way to prevent (or at least significantly obfuscate) hard drive access from the live CD?

I'd like to distribute some customized CDs to high school students as a learning tool, and I really don't want them to be able to intentionally or unintentionally use the disk to trash files on a hard drive due to litigation issues.

Thanks all,
oznozz