I jotted this one down months ago, just before final exams, when I knew I wouldn't have time to work on it. (There's a teacher who comes in early and practices in an empty classrom...) I wish I had remembered it when Will Shortz had his Spoonerism competition recently. I have to check my notes more often.
And these images are based on some that I saw online, only without Kenny going through the motions.
See the difference. The calculator does, too. One Celsius degree is not the same as one degree Celsius. The former is a unit of temperature; the latter is an actual temperature reading.
The first equation represents two positions on a scale. Those positions could just as well be named New York City and St. Louis. You couldn't add those two values together. However, if they had values on that scale, you could subtract them to find a displacement; i.e., how far apart they are. And the original equation could be changed to subtraction and yield a correct answer.
This brings me to a tip that I give my students, usually when reviewing percents (sales tax) and Order of Operations. I tell them that you can add dollar amounts, subtract them, or even divide them (in which case, have them notice that they lost the dollar sign and have them explain that back to me). However, if you ever find yourself multiplying two dollar amounts. Stop! You're most likely doing something wrong.
Which brings me to this graphic that I created, using Google's calculator:
What are square dollars? That's silly! Our dollars are rectangles.
I was looking at my Google Analytics numbers, which I expected to be depressing because I've taken a lot of time off lately, and there was a little bit of a silver lining. There was not only a pick-up in the number of stumbles sent by Stumbleupon, but the number of pages (other than the main site) had increased dramatically. So much so that I can list the Top Ten because there were more than ten on the list.
Mr. Burke is a high school math teacher in New York as well as a part-time writer, and a fan of science-fiction/fantasy books and films.
He started making his own math webcomic totally by accident as a way of amusing his students and trying to make them think just a little bit more.
Unless otherwise stated, all math cartoons and other images on this webpage are the creation and property of Mr. Chris Burke and cannot be reused without permission.