Are you sure you should be taking apart school property? ;)
Anyways, you need to remove all the rubber feet on the calculator since there are screws under each of them. Also, I believe there are more screws located underneath the battery. You will need to remove the battery cover, then remove the battery itself, then you should be able to see the screws. Remove those and you should now be able to pry apart the calculator.
Could you please tell us exactly what’s wrong with your calculator? It may not require you to disassemble it.
If your calculator is acting like that then there’s most likely a software issue and (hopefully) not something with the hardware. There are a few things you can try to get the calculator working. (I got this info from TI Planet )
Press the reset button, then hold down the keys:
(Some combinations are handled by the boot1 (earliest stage) and cause their effect as soon as the device is (re)starting.
Others are handled by the Boot2 and cause their effect when the loading bar is over 50%.)
This launches the diagnostic software, if present (non-dangerous choice, AFAIK)
* [esc]+[menu]+[-] (Boot1)
This goes to the Maintenance Menu (allowing you to delete the OS, etc.) (no effect if nothing if cancelled - not dangerous)
* [doc]+[enter]+[EE] (Boot2)
Try getting to the diagnostic software, if you can, see if you can find what's wrong. If you don't have diagnostics software proceed to the next part
Try using the Maintenance menu to delete the OS then get the latest OS from TI's website and install TI-Nspire Computer Link (for windows and I think also mac) then send the newest OS to your calculator. Hopefully your calculator should start working again, if it doesn't, try launching the diagnostics again. If diagnostics still doesn't work please reply and I'll try to get some more help.