Dyslexia refers to the phenomenon that children with normal intelligence and no obvious physical impairment, but their reading performance is significantly lower than that of children of the same age by more than two grades.
Xiaohua was supposed to be in the second grade. His Chinese teacher thought he was lacking in literacy and was afraid that he would not be able to keep up with the class, so he suggested that Xiaohua go to the first grade again is dyslexia according to the above definition.