In school when we got introduced to calculator, the teacher told us that he was not here to teach it to us. Only maybe guide us, we had a few lessons of us sitting down with the manual and having to learn (mostly by ourselves, but he would also help) how to use the calculator we chose. After that, it was to each its own, he wouldn't give any explanations...

This is IMHO fair, he was anyway teaching us math, not using a calculator.