Teaching sometimes feels like an activity that happens in a bubble. It is neatly contained within the four walls of the classroom, usually to a group of children of similar age and ability, with relatively similar life experiences and broadly consistent views. Teachers can plan for this, and they can assess what happens: neatly, consistently, fairly. What teachers can never plan for is what happens outside the bubble. This, I would argue, is where teaching is at its most powerful. When students leave a classroom, despite popular myths about teenagers, they do actually like to continue to engage with the topic that has been under discussion. This is particularly true of conversations about controversial issues, such as abortion, euthanasia and community cohesion. Young people are inquisiti