'Just occasionally, some of them turn around and say thank you, and that's what keeps you going.'
It can be a struggle convincing teenagers of the miracle of maths - especially when the thought of Pi just makes them hungry.
But there is no end to Mr Thomas' patience and perseverance. The most important numbers of all for him are the students' GCSE results and he is determined that his class will score highly.
Keeping a room of 16 year olds focussed on algebra is no easy equation, but for Mr Thomas it's what teaching is all about, and he's always ready to bring out his Welsh wit when needed.
