#1
Hey guys, I'm looking for a good opeth song to present to my music theory class. I'm looking for something that starts off acoustic with clean singing and progresses to great heavy riffs, and a mix of clean and brutal vocals. Suggest every opeth song you can think of that fits that description.
#2
you could always just go with black rose immortal and waste half your class right there

serenity painted death, but that starts off heavy with an acoustic mid-section

i like to play demon of the fall and credence together as if they were the same song, but again that's starting off heavy

you could do face of melinda, but i wouldn't say that any of the heavy riffs in it are 'great'
O what a disgrace if such a despised and base race, which worships demons, should conquer a people which has the faith of omnipotent God and is made glorious with the name of Christ!

The music winners listen to
#3
That describes most of Opeth's older material, lol.

But, try:

Harlequin Forest
A Fair Judgement
The Drapery Falls
Hessian Peel
Atmospheric dark metal w/ black and death metal influences:
(My Soundcloud page):

Pestilential Flood
#4
The Moor from Still Life

actually that whole album is pretty good for your description...although I don't remember if there is a lot of clean singing in "the moor" but the music is as you want.
#7
^^I recommend not listening to this hipster, for any reason, ever.
Atmospheric dark metal w/ black and death metal influences:
(My Soundcloud page):

Pestilential Flood