Yesterday I covered a 7th grade math class. After their warm-up, I was to go over any homework problems that they wanted to see done. Every period requested the same 4 problems, so by the end of the day, I was pretty good at them.
For one of the problems, they had to divide two negative mixed numbers. Before converting to improper fractions, I said to the class: "A negative divided by a negative is..." This has been so ingrained that they replied with the correct, "A positive."
I did this so I wouldn't have to keep writing the negative signs.
But before I could go on to the conversion, one boy in the back asked, "Then why do they say two wrongs don't make a right?"
Interesting question. That would have made an excellent discussion. But I had been warned that this class could easily get off task, and they were 7th graders. We would not have had a discussion. We would have had a shouting match.
I know this from experience. Classes that were as wound up as them (one boy thought it funny to get up and dance behind my back) would have veered way off topic, and we would have wasted the entire period. They would have gotten what they wanted--not to do the worksheet assigned.
I replied to the boy: "That is not a math question. Although, three rights do make a left."
Mistake. They didn't get the reference. (I wish I remember which comedian made that joke.) And it took my stern voice to get them back to the question at hand.
I don't know why I bother to tell jokes in class. I'm the only one that ever gets them.