Being a teacher and administrator myself, I know that some teachers just will not admit a mistake because they think it takes away their authority. I try hard to coach my teachers that admitting mistakes actually teaches the students to respect you and to make yourself more approachable.
MAN, is this ever true!
I've learned, myself, that there are a few very valuable phrases I'm glad to put into practice as a teacher and wish other teachers used more often:
1. "I don't know! Let's find out."
2. "I was wrong."
3. "I'm sorry."
