In grade-high school we called that Mr/Ms/Miss last name . But many of them were friendly enough that you would learn their first name, but they would tell you not to use it until after graduation. because after graduation you can be friends.

In college... Most of my teachers at least the art ones didn't seem to care if we used last names. Only one did, and she was the one class that i didn't learn anything in. i usually went with just not saying names. ^^; i never know what to call them. I'm very used to calling teachers by last names its hard to switch.