(n.) The act of deriving equations just for the sake of deriving them, at no apparent gain to the student.
In verb form, to mathturbate is to perform such menial mathematical labor.
mathturbatory: characterized by excessive mathturbation
"The professor spent three hours deriving the equation on the board because he thought it would help us understand the concept better; really, however, he just confused us with his senseless mathturbation."
"The homework problem required hours of mathturbation, with the end result being a simple identity that appears in the index of every text."
Jacking off
Whacking off
Beating off
Smacking the ho
Beating the pig
Whipping the Wayne
Slapping the salami
Whacking the wand
Punishing the pubs
Burning the beet
Beating the beef
Beating the meat Jerking the jerky
Jerkin' the gherkin
Working the slave
Choking the chicken Or
In redneck terms
Buttering the corn
Revving the engine
Or
Hunting the deer