Is your child a confident writer? When I was younger I found myself less inclined to do schoolwork because although I knew the answers, I was an extremely slow writer. I knew perfectly well how to write, that wasn't the problem, it's just that I was physically slow. I was constantly being kept in for not having finished my work and I was always miles behind the rest of the class when we were copying notes made by the teacher. With your son now being seven, it would be now that this sort of problem would show up, becuase most of the children in his class are now able to write, so physical slowness in writing would be more noticeable. It would have gone unnoiced before when other children were struggling to learn how to write. If this is the problem, I would suggest speaking with your son's teacher and the you and the teacher could work together to decide how to best meet your son's needs in this situation. I wish you the very best!