Wouldn't it be great if, before you had to answer this question, you knew what your principal used to teach? Although the interviewer may have a copy of your college grades in front of her, she probably does not have a clue about your academic success before college.

This question may be a good opportunity for you to explain some grades on your college transcript that should have been better. Be careful about "blaming" a poor teacher or a poor learning situation. Your interviewer does not want to hear "excuses." Don't hesitate to blame yourself for not being prepared, for not studying enough or for not devoting the time necessary to succeed in a particular class. Turn the experience into a positive one by assessing what you learned from the poor grade.