Does the child really need extra classes?

The results of the child's exam are out, and they are not ideal. The child's explanation is: the poor performance this time is actually because I made mistakes in a few questions, but I actually know how to do them, so there is no need for extra classes. Should I believe the child? Perhaps I should observe for a while and wait until the next exam? Many parents, due to the inevitable mentality of wishful thinking or relying on their fragmented cognitive preferences, tend to address immediate concerns rather than seizing the opportunity to help their children solve problems.