Dean Jones says:

"Perhaps I can adjust the offer a bit: How about SIX PER ACADEMIC YEAR?"

Your response:

1.  That is better...I am willing to supervise FIVE per year.  Yes, that is the right number of undergraduate independent study-type projects to supervise.

2.   That is better...I will agree to SIX per year is the right number of undergraduate independent study-type projects to supervise.