Laila,
If you edit the student database in the software and save it, closing and reopening the software should not effect the data. The devices should also stay assigned to the previous class without having to re-register the devices. What version of ActivInspire are you using? What is the firmware version for the ActivHub and the driver version listed in the ActivManager hardware tab? What is the firmware version on the devices? To locate this, select Menu, Diagnostic. (case# 252237)
Thanks!