Watch Edwin Durell's DREAM GIRLS, w. Melissa Melendez,
Taija Rae, and Nina Hartley.

The first scene filmed at a school classroom, with
Melissa Melendez as the teacher and one single student
left (it is a exam class). It is the best filmed I have
ever seen, with best lighting, and very understated
acting. Melissa Melendez is wearing those short high
heels (not horrible tall platform heels, but short ones),
and has just a hint of a smile on her face as the sequence
unravels. It is mostly dialogue-less, as she approaches
her student (only guy left in the class apparently failing
in the exam as he tries to cheat) and they gradually
get it on with the sex. This is a very well made scene,
it builds up to eroticism. Compare this with today;s
blowjob scenes where the guy
is slapping the girl and not even letting her proceed
with the blowjob. Just because everybody has a digital
camera !

Check out the threeway between Paul Thomas, Nancy Hoffman, and Eileen Welles in Bob Chinn's "Candy Stripers". The quality of the film itself looks pretty lowbudget. But the editing is exceptional, and that scene in particular has intense heat and chemistry. And it's written well enough to be believable.