730-430 (30 min lunch) 8.5 x 5 = 40+
can't give you an exact minute by minute breakdown, but there are plenty of incidentals that add up that you don't realize that you don't expect.
I've gone and helped her do some things in the classroom myself on Saturday such as setting up a power point projector, hanging up posters, decorations.
You have the paper grading, phone calls, before/after school tutoring for those that ask and make appointments, after school meetings, lesson plans and more that I'm not thinking about all add up to anywhere from 60-70 hours a week.
(again, I didn't say "70 hours every week")