Well done Eric, I remember a teacher when I was at school who was thought of a way to fool the inspectors. In those days the inspector usually stood at the back of the class and asked the teacher to "Carry on as normal". During the lesson he asked a lot of very hard questions and every kid in the class put their hands up to answer and they always answered right, which impressed the inspector very much and the teacher and class always got a glowing report. The secret was, that before the inspection he told all us kids "If you know the answer put up your right hand, if you don't know the answer put up your left hand."
Bill