It is normal for a five-year-old child to go to the first grade earlier. In the first grade, they have to recite more Chinese than they think, and younger children have strong memories and are not easy to forget. Unlike math, they don't have enough understanding until they reach a certain age.

Don't worry, don't ask your child too many questions, and don't scold him, which will make him feel inferior. When he reaches the senior grade, he will not be affected by his age, and his math scores will naturally pick up.