Unfortunately For My Student, This Is a Question About Cantor's Diagonalization Argument

I'm halfway done. Ugh.

Don't even get me started on the students who said that 3/51 is an irrational number (because the repeat is too long to fit on their calculator screens).

Or the students who got wrong: "True or False: There are different sizes of infinity." Especially since at the beginning of class on Monday I wrote on the board, "There are different sizes of infinity" and then put two boxes around it and about a dozen stars next to it and then a few arrows pointing at it and then said to my students, "If you learn only one thing in class today, this should be it. This is the most important thing that we are doing today. There will be a true-false question about this on the exam."

Ugh.