This is actually another good reason to stop this sort of behaviour. There are people, often single and bored, who have nothing better to do. There are people who would rather avoid their other halves and kids. Quite often, I'm sure they mean no harm, but it normalises a certain pattern of behaviour which doesn't work for most people with kids. And then again, I suppose some of them are scared or trying to compensate for lack of ability. Terrible as it may be to say right now, perhaps this is a good time for teachers to say no. It would take a pretty self-destructive and petty tyrant to fire talented and irreplaceable teachers, one not long for the profession. If the unions really considered the power of collective action, not even anything as severe as work-to-rule, then I think change would come quickly. But maybe I am just some commie dreamer.