A traumatic but illustrative story:
A couple of years ago I took over a Year 11 class from Ms Ind. Naturally I was nervous, because I felt so uncertain that I would be able to maintain her high standard of teaching. It turned out that I was right to doubt myself. In my very first class, as I tried to interest my students in information about the nervous system, there was a crisis. One of my students suddenly became very pale and looked as though he was about to faint.