I have said much that I think needed to be said about the down sides of the NSpire CAS calculator. This was because I had heard enough promotional peddling from other people about this calculator that I thought the air needed to be cleared and people be brought down to earth about the calculator. I had gotten enough hits on this topic that I thought others must be concerned as I am too.
This time, though, I would like to say a few things about this calculator that make the CAS indispensible. For Grade 12 math, I find that, because the CAS hands you the answers, it is easy to make questions for the students using it. Also, when it comes time to correct, I can enter a calculation a student gives me which I hand’t thought of, and quickly check if 1) expressions are equivalent to my answer key; 2) their calculations lead to the same answer as mine when it becomes unclear, and the student hasn’t explained their logic. Marks come off whenever students make me go to this trouble, but it is good for assigning partial marks, and saves me lots of time.
I was also able to write answer keys very quickly for things that would take some time in calculating and be more error-prone, such as cross-products and simultaneous equations in three unknowns. The latter could be found using the rref() (that is, “reduced row-echelon form”) function and converting the equation system into a matrix.
Even as I have computer-based software such as Maple that already has a CAS, the NSpire CAS is much more portable, enabling me to do quick solving or graphs anywhere so there is less of a need to have to lug my laptop around all the time.