According to the modern concept of health, health includes four levels of health: psychology, physiology, social adaptation and morality. However, the health of preschool children usually includes only two aspects: physical and psychological. According to Piaget's cognitive development theory, preschool children's moral cognitive development is in the pre-moral judgment stage, and they do not have good moral ability. Therefore, it is not appropriate to choose moral standards to measure the health status of preschool children. Similarly, preschool children have just entered the society from the family, and their social development is in the initial stage, so social adaptation is not appropriate as an evaluation index. In view of the development level of preschool children, their health standards usually only include physical health and mental health.
Preschool children are often in a state of exchange between health and disease. Because preschool children's physical development is imperfect, their physical function is unstable, their disease resistance is low, and they are easy to be infected with pathogens and suffer from many diseases. At the same time, Xue Qian's children have strong metabolism, strong repair ability and quick recovery after illness. Children in life are often in the process of dynamic changes in health and life, and few children have never been sick.