As a former teacher I say yes... It's funny, but I was just thinking of this before I came back.
This is primarily because I taught art and I only graded on their effort.
Not everyone is a born artist, so their grade was a flat grade. No curves, no tests, no final. Each day was there only chance. When the project was due, I cared very little about whether I had40 Picasso level artists, and more about whether they demonstrated that they cared!
I understand that in math, grading can be far more objectively determined. But if their behavior stinks, their grades will reflect it anyway. They can't learn when you've sent them out of your class. I say - Let them determine their own grade in that respect. Otherwise, their grade will be far better should they pay careful attention.
Having said that, there are those who lose interest due to discouragement stemming from an innate disability. I do, however, think this has to due with hormones. In high school, I cared very little for things that were not beautiful and romantic. I loved Literature, English, Art and even science because it was visual and tactile. Where as in Math, I languished due to my overactive hormones and an imagination that the math did little to stir. By college, my Math scores sky-rocketed. Funny analogy, as Freud would call a Rocket a symbol of potency. I got in trouble for drawing graphic sexual images in high school math. I hate to confess it, but my behavior in Math stemmed from a teacher that did very little to make Math real and fun... it should be. In college, not only had I become sexually active, but perhaps enough so to have gotten it out of my system so as to focus where I needed to focus.
Back to your question -- behavior as I point out from time to time here on HPs, is the product of thought. What and how you think -- more specifically -- what you think about determines how you behave. Their interconnection is maximal. When a child is in class, he needs to focus on the material, or be willing to undergo the consequences of his behavior: A bad grade.
Depending on the grade level, behaviors stem from a host of causes. For some, hormones, others - a genuine lack of attention at home, and an opportunity to get it at school from peers. Unfortunately, since kids and parents are now practically the owners of the classroom, its difficult to make an example of them without a scandal ensuing. In the end, Parents need to stay out of the class and KICKASS@HOME.