MPs call them supplementary questions. They are the cruise missiles of politics, designed to take ministers by surprise and hole them below the water line. So it's a touch unnerving to come across one in a classroom. "Sir, will global warming make sea levels rise?" It's Kieran launching one of his innocently wrapped questions. Don't panic, everyone agrees that sea levels will rise, play for time.
"That's a good question Kieran. Does anyone want to have a go at an answer?"
Arms remain fixed to sides, mouths zipped tightly shut. The class has known Kieran for three years. They are going to leave bomb disposal to the experts.
"No? Well, it's easy really."
Good grief. Why did you say that?
"As temperatures rise some of the polar ice will melt and levels will rise."
Success. You managed to avoid a question mark at the end of the sentence.
"But ice takes up more volume than water, and floats with most of the mass below the surface. When it melts it will occupy less space, surely?" Direct hit. You are now doing your well-known impersonation of a stranded goldfish.
Lots of faces grinning at you. Keep calm. Breathe slowly. Count to 10.
"That's a really good point."
Kieran's last really good point came during a presentation by the local vicar. Halfway through a homily about tolerance and forgiveness Kieran had innocently asked whether wars were bad. The vicar had replied that they were and Kieran had followed up with a question about St Augustine's doctrine of the just war.
The local authority's gifted and talented adviser came to see Kieran, expecting to find a bullied little boy wearing horn rimmed specs and an otherworldly expression. Not quite.
The bell goes. Kieran runs outside to thrash his mates at football. A light comes on. "The South Pole," you yell. "That doesn't float, that's why the levels will rise."
"Well done, Sir," says Kieran.