What's wrong with this sentence (other than that it is incomprehensible out of context):
Because I don’t know what you don’t know.
MS Word is telling me that this is a sentence fragment (I disagree). MS Word said the same thing about an earlier version of it:
Because I don’t know what it is that you don’t know.
I'm trying to write a FAQ for my syllabus (don't worry, I'm teaching math, not English). One of the Q&As goes like this:
How come your lectures are so terrible? Because I don’t know what you don’t know. If you ask more math questions – even stupid ones – I will get a better feel for your confusion.
I think this is a perfectly reasonable sentence. It means: I don't know what piece of information you don't have in your naive, little student brain, which makes you incapable of understanding my perfectly clear explanation of integrating using the shell method to calculate the volume of a solid generated by revolving a region outlined by a few functions around another line (I mean, really?).
The subject is "I". What am I doing? I'm not "knowing", the verb. And then the rest of the plain English sentence.
Or maybe is MS Word even stupider than a calculus 2 student?