This will allow you to bypass the security that the school district put up, but the interface is very basic at best.
This client is intended ONLY to allow you to send/receive e-mails; it isn't intended to be some rebellious thing.
(Note- If you do want to continue using GMail and send/receive files, there is always the option to forward e-mails sent there to a different e-mail address, such as yahoo/hotmail. Just check the options)
[Note- Use at your own risk!]