You may be interested to know that in the South (or maybe it's just a "these days" thing--not sure, info from my sister the teacher who taught in North Carolina and now teaches in DC, but also simply teaches in the present whereas I went to school in the past) they go with Mister/Miss First Name.
The only place I've heard that is in kindergarten or the early grades of elementary school. But after a certain age in my schools in the south, we always did the Mr./Ms./Mrs. thing.
no subject
no subject
no subject