At some point the iPads at your school will need to be updated.  To update your device you will need to change the AppleID.

Step 1: Open Settings on iPad

Step 2:  Select iTunes & App Store

Step 3:  Touch the Apple ID box at the top

Step 4:  Select Sign Out from Pop up.

Step 5:  Touch the Create New Apple ID or add yours if you aready have one.

You need to sign out of the FaceTime app as well.

Step 1: Select FaceTime from Settings
Step 2:  Select Sign Out from Pop up

To learn more visit: http://support.apple.com/kb/HT2534