Charlie Laurie, 15, has been in specialist dyslexia schools since he was seven. At 11, he arrived at Mark college in Somerset, working at an eight-year-old's level in maths.
"When I was little I could do adding and subtracting, but as soon as it got more complicated I couldn't get it at all. At primary school I remember the teacher would ask my friends questions, and they'd go silent for about 10 seconds, put their hands on their heads and come out with the answer. So when the teacher asked me a question, I would put my hand on my head and do the same. Just to see if it would work. But it never did.
I never understood multiplying. Or dividing. I can't do things in my head without writing it down. Even two times three. I can't do algebra: I don't understand what the letters are there for. It's really confusing. But I've been lucky: I've always had help and I've never really been made to feel bad.
There's about seven in my maths group, and I've had one-to-one teaching, too. You feel such a pain asking every single time, "Can you go through that again, and again." But last year it all started to click. I struggled and struggled and suddenly I got it.
Things I'd never understood, now I understand. It's strange how it happens.
It all unfolds. It's partly finding ways round things. Like I still can't multiply by six, but I can go off in fives and add one.
When you get one bit of maths it can help with others. I'm predicted to get a C grade at GCSE now: I'd never have thought that was possible."