help with javascript quiz

Hello all, I'm new here. Kind of a newbie to javascript as well. I've used it before, but this is my first time seriously working with it. For a computer class we were assigned to turn this page into a true/false quiz.

(For example, the first line "what is the exam grade?" would be changed to something like "the sky is blue" you would say T or F, the next line would say yes or no and the comment would say great job! or something.) I've changed all the variables and I keep getting "undefined" in the second box. This is driving me nuts. Everyone else seems to get it and I don't know what I'm doing wrong.

I would love you forever if you could help!

I can edit this and post the changed code that I've used, but I doubt it would be of much help.