I'm not against using graphing programs in an educational setting, but I'm very concerned about limiting their use. I want students to know how to graph whatever it is they're supposed to graph, not just know how to use a computer or graphing calculator to generate a graph. As far as presenting material goes, I see that such programs have a valid place in the classroom.
It's one thing to say that all programs are not created equal, it's quite another to say that many don't graph correctly--but many don't! I have a "litmus test" function I use to determine if a program meets my minimum standards. If the program graphs it correctly, the program is probably good; if it doesn't graph it correctly, then I don't look any further.
What is the function, you ask? y=x^(2/3), or x to the two-thirds power. Some programs can't handle x being negative, others can't handle that the y-values are always non-negative. Additionally, the graph should be symmetric about the y-axis.
I know there are many such programs out there, most of them free, but one I've found recently, and one that's very easy to use, is the "Graph" program that can be downloaded here.
I think Macs come preloaded with a graphing program. If not, then please leave a comment about where you can download a Mac-based program that meets my litmus test above--same goes for pc-based programs. Have a favorite graphing program? Let us know!