I majored in and received a BA degree in Mathematics.
I took advanced courses in Algebra, Calculus, Differential Equations, Statistics, Probability Theory, etc while contemplating a possible career as a math teacher. Instead, a couple computer-programming courses changed my course toward a 30yr career as software engineer in Silicon Valley.
Jump to present day 4th grade class. Despite my eventual career change, I am still fully equipped to handle even the toughest problem any 4th grade math book could throw at me. Therefore, when one of the kids approached for some help, I knew I could navigate and guide him to the proper result.
The word problem involved patrons at a movie theater with four multiple-choice answers. Should not be any problem AT ALL for a substitute teacher with such impressive credentials. I even had the TE (Teacher's Edition) with the correct answer indicated!
However, even though I read and reread the problem at least three times there seemed to be some additional data missing to satisfy for any of the four possible answer choices.
This isn't the first time I've come across incorrect or confusing word choice problems in classroom math books. I explained to the class that there seemed to be some kind of error with problem #4 and to go ahead and skip it.
"Your teacher will deal with it on Monday...."
My end of day status report included a statement that math problem #4 on page xx seems to need more information to solve it. I made a copy of the page and brought it home to show Claudette.
Claudette, who also has a BA in Math (with a better GPA), took one look at it and says:
So? The answer is 'C', right? Subtract the number of people attending the afternoon show from the number attending the evening show and you get answer 'C', right? I take back the page. I re-read the problem and it is obviously correct. The indicated answer is indeed the one marked on the TE page.
I must have had some kind of brain fart in class to not "see" the obvious! AND I made it worse in that I left written evidence of my incompetence by documenting it as part of my end of day note for the teacher!!