Authors:

If you don't let a teacher know what level you are -- by asking a question, or revealing your ignorance -- you will not learn or grow

Stephen R. Covey (1994). “Daily Reflections for Highly Effective People: Living THE SEVEN HABITS OF HIGHLY SUCCESSFUL PEOPLE Every Day”, p.132, Simon and Schuster
If you don't let a teacher know what level you are -- by asking a question, or revealing your ignorance -- you will not learn or grow