Math is not English. You can not proofread it even the solution is wrong. Kids might think that they knew the concept, but in fact, they didn't. They would still get confused under different circumstances. So I think problem solving skill should be the focus for tutoring at home. Also encourage him to solve the problems using multiple techniques. It is like the proofreading in writing. Once he truly master the concept, he may try some fun activities, for example, Many kids on AoPS like to make up problems to challenge each other.