Another common example of the dangerous subtext is teacher nagging. The class is working semi-quietly, the noise levels rise, as they always do, after about three minutes. The teacher says, ‘Year-8! You’re doing this quietly.’ The level drops. After three minutes, it rises again. The teacher is now a little more insistent. Year-8! I told you! Work quite!’ The process flows on. Every three or four minutes, there’s another teacher grumble and each one is a little more tetchy than the last. You could draw a graph of it.