I was guilty of being one of those students once. I wanted to take up oils and decided to take a class on it. I'd never learned about art through a class but with oils I wanted to know a couple of key things about it before starting (like whether it needs to be mixed with a thinner etc) and I found a small art store that had some classes.
They tried to start me off that day on a landscape, and I bought the canvas and paint and got started. As soon as I'd figured out what I needed to know I asked for another and painted something more in line with what I found interesting at the time.
It was a bust of a bald blue head with its mouth open and screaming, and in the place of the eyes was two screaming mouths as well. I rounded it off with a bar code on the forehead and was done for the afternoon (thus ending my one and only day of art class).
The teacher and other students were shocked by it, and couldn't stop talking about it and every time I went back to buy more canvases they'd ask about it till I finally ended up giving it to them.
I wasn't trying to shock them, or at least wasn't only trying to, but the landscape they had me paint was boring and I wanted something that said more than "cottage and a tree on a hill". What was in my mind those days was dark and I liked dark art and dark imagery and I think it was just who I was at the time even though I did like the reactions I got from the art I would have painted dark or shocking themes because that's the mood I was in back then.