For Math 6-8, most schools are choosing to use the TI-30XIIS or the TI-34MV. Both are acceptable to use. To prepare the units for the assessments, simply clear the memory. AVOID THE TI-30XS MV as it is NOT acceptable for NYS exams.
For the NYS Math Regents exams, here is a list of TI models that are accpetable: TI-83+ TI-84+ TI-84+ Silver Edition TI-84+ C Silver Edition (Coming this March) TI-Nspire Touchpad TI-Nspire CX
Preping them for assessments, the TI-83+ should have the memory reset (2nd Mem Reset All)
For the TI-84+ Series and TI-Nspire Family, I recommend Press-to-Test.
Contact me directly with questions, and before you ever order, feel free to call or email me with questions.