Adversity is a severe instructor, set over us by one who knows us better than we do ourselves.
As in everything, nature is the best instructor.
Fear is a great instructor.
Fear is an instructor of great sagacity, and the herald of all revolutions.
Back in those days intimidation was the greatest tool the drill instructor had. Without that tool, he would not have had control.
The bad news motivated the drill instructors that much more.
Once I win, everyone will know who my instructor is in mixed martial arts.
He who has failed three times sets up as an instructor.
The closet is the best study. The commentators are good instructors, but the Author Himself is far better.
Mistakes are their own instructors