There's an interesting case around me when I was young.A girl who might have a relatively higher intelligence went to the school when she was 5 while the average schooling age was 7 at that time.And she even skipped one grade in the school.Maybe with the huge advantage,the girl became self-satisfied and loose so that the next year she stayed in the same grade for one more year.Now I though her IQ developed faster,her psychology didn't keep the pace with it,so she got the stay-down in the school. There's an interesting case around me when I was young.A girl who might have a relatively higher intelligence went to the school when she was 5 while the average schooling age was 7 at that time.And she even skipped one grade in the school.Maybe with the huge advantage,the girl became self-satisfied and loose so that the next year she stayed in the same grade for one more year.Now I though her IQ developed faster,her psychology didn't keep the pace with it,so she got the stay-down in the school.