[eslifka]

I don't have any references for you, but my middle school and highschool required graphing calculators. And they very strongly pushed the ti-83+, claiming that students would be horribly lost if they couldn't follow along with the teacher's instructions. In reality the teachers were all incompetent with the calculators and the school wanted everyone to have an 83+ because that was the only platform on which the teachers knew the process for erasing the memory.

[_phred]

I can correlate the "strongly recommended TI part," having graduated HS in 2001. I used an HP-48GX and yes, at times, it was hard to adapt the teacher's instructions. My friend and I both had 48's, and we helped each other work it out. When we got into symbolic manipulation, statistics, and inspecting 3D graphs, the HP left the basic TI models in the dust.

But yeah, no problem using a HP graphing calculator when I was in high school; took trigonometry, AP calculus, AP physics, and the SAT all using that calculator. Even had a full year's trig notes stashed in there, though I honestly didn't use them on any exams; just handy for calculus homework.