However, earlier in the term I managed to fail an observed lesson, observed by one of the senior managers who hates the way I teach. At the end of the same lesson, one of the pupils told me that I had delivered the best explanation that she had ever heard.
Go figure.
So tomorrow I guess I need to cover myself by telling the teacher observing that she should just ignore the crap teaching part and keep her eyes on the screen. That should do it.