My high school basically expected you to get a TI 83. My dad decided that it was a ripoff and we got Casios instead. Casios? Oh, nothing survived in my backpack. Nothing, so Casios.
Eventually my school got around to issuing me and my acadec teammates TI-89s.
Looking back, I still think the most useful aspect was being able to see what calculation you typed in, so you could check for typos.
similar situation, but in my case the school wanted everyone to have a TI-82. when we went to walmart, they were out of 82s, so my folks splurged and bought me an 85 without knowing the incompatibilities.
not being able to link with peers and teachers sucked, but that calculator gave me my first taste of hardware -- building a pc link cable by cramming two diodes and half a link cable into my pc parallel port, and first taste of z80 assembly
Eventually my school got around to issuing me and my acadec teammates TI-89s.
Looking back, I still think the most useful aspect was being able to see what calculation you typed in, so you could check for typos.