to be acting as you do when you are working as a teacher, lawyer etc., which may be different from the way you act in other situations
I was wearing my teacher's hat at the meeting. (Cambridge International Dict. of Id.)
Wearing my teacher's hat I am excited by some of the modular schemes available at A-level, particularly those which enable the modules to be examined throughout the course and points aggregated for a grade at the end. WebC
When I was wearing my teacher´s hat, I was in a classroom with 16 students working on degrees in teachimg English as foreign language. Google