No, the TI-8x series used in high schools use TI-BASIC, a version of BASIC that makes most other BASIC dialects look good by comparison. Seriously, it's rubbish.
You clearly haven't tried the BASIC on the TI-89, which is capable of symbolic math. Not only does BASIC get full access to the CAS, it also has some really powerful features I've not seen anywhere else - for example, #("some_string") will return the value of the variable named some_string (they call this "indirection").
...So, you've never used LISP, or played with a language with eval in it? In either, the above isn't exactly built in, but it is trivial to create.
But yes, being unaware of the 89, I was talking about the Z80 calculators that make up the rest of the TI-8x range, which are still used in schools to this day, which are programmed in a rubbish version of BASIC called TI-BASIC. It sucks. The 68k calculators, like the 89 and the nspire are programmed in a completely different and much better version of BASIC. This is also called TI-BASIC. This leads to much confusion, and to make it worse, there is a third TI-BASIC, which is also completely different, and was used in the computers made by TI.