“21 seriously cool careers that need maths,” says the poster on the wall of one of the mathematics department classrooms. Being a teacher is not among the twenty-one.

Once, I asked a class in Dublin, “would you like to be a teacher?”

I remember that just three of them answered “yes,” and the answers were for things like having long holidays rather than anything to do with the job itself. The rest of the class told me that school was boring and being a teaching would be boring. Perhaps it …