I. Growth and development Before the age of two, children usually grow fat, and after the age of 3 to 4, they gradually become thinner. In pediatric clinics, we often see parents with children aged 3 to 4 or 5 to 6 years old, with “thinness” as the main complaint, asking the doctor for a thorough examination. After the examination, when the doctor says the child is not sick, parents often with a puzzled look, continue to ask: “Nothing sick, why so thin?” Children do not grow fat for a variety of reasons, in addition to factors related to physical fitness, nutrition, diet, sleep, disease, exercise, genetics, etc. Children of this age are generally thinner than when they were children. This is because children at this age, the body develops much more slowly than in infancy. Children between the ages of 3 and 6 years old, on average, grow 5 to 6 cm in height each year, while their weight increases by only 1.5 to 2 kg per year. In addition, the brain function of children at this age is becoming more and more well developed, and they are more and more active, with little idle time except for eating and sleeping, and the caloric consumption in their bodies is relatively increased, so their bodies begin to become thinner and their subcutaneous fat decreases. This shows that children of this age are not as fat as they were when they were young, and are generally normal. As long as growth and development are normal, there is no need to take your child to the hospital for a checkup. To know whether the child’s growth and development is normal, you can judge from the child’s height, weight, chest circumference, head circumference and several other aspects. Weight reflects the child’s nutritional status, weight can be calculated by the formula “weight (kg) = age × 2 + 8”, for example: the weight of a 3-year-old child is 14 kg, 6 years old is 20 kg, the child’s weight is more or less than 10% of this standard can be considered normal, if it is more than 15% below the standard weight, it should generally be regarded as Low weight, may be due to malnutrition or some chronic wasting diseases; if higher than the standard weight of 20% or more, can be diagnosed as obese children. Height and the number of teething can reflect the child’s skeletal growth and development. The height of a child at this age can be calculated by the formula “height (cm) = age x 5 + 80”. A height below 30% of the normal standard is considered abnormal and may be due to rickets, malnutrition, chondrodysplasia, cretinism, pituitary dwarfism, diabetes, etc. A normal child will have all 20 baby teeth by the age of 3, and one permanent tooth at the age of 6, i.e., the “sixth age tooth”, and will begin to replace teeth. Chest circumference can reflect the development of the child’s chest, chest and back muscles and lungs, the child’s chest circumference at this age can be calculated by the formula “chest circumference (cm) = head circumference + number of weeks of age”. The size of a child’s head circumference is generally related to brain development, and is generally 49.1 to 50.8 cm for boys and 48.1 to 50 cm for girls between the ages of 3 and 6. If the head circumference is too small, it may be a congenital microcephaly; if the head circumference is too large, it may be hydrocephalus. Motor development 1. Gross motor development: Children aged 3 to 4 years old can walk around independently, run, jump, climb up and down on the climbing frame, keep their balance when jumping from high places, jump high and long, throw darts, and turn around with their eyes closed. In daily life, they can wash their own face, wash their own hands, and put on and take off simple clothes, shoes and socks. Children 4 to 5 years old can jump on one foot, slide, and play with the bucket. Children 5 to 6 years old can run and jump freely and can walk continuously for 20 to 30 minutes. When running, they can dodge and chase, run in a coordinated manner, have better balance, shoot and kick the ball, and can shoot and kick while running; they begin to like group games, and often change the rules and create new tricks while playing; they can imitate adults, use dishes, and do simple chores such as sweeping and wiping the table, but they have no patience in doing anything. During this period, parents should try to create good places for their children, often take them to children’s playgrounds and more respectful activity places to play and run, consciously improve their motor skills. 2, fine motor development: As the brain function and small muscle development is becoming more and more perfect, 3 to 4 years old children can do fine movements, such as origami, cut and paste, can draw simple flowers, trees and human figures, can write simple words. Children 4 to 5 years old can draw more perfect little people with heads, bodies, and limbs, and can draw round, triangular, and square things, such as the sun and apples. Children 5 to 6 years old can write simple Chinese characters and Arabic numbers up to 10 in pencil, and can put on their own shoes and buckle them. During this period, parents should encourage their children to do more hands-on practice, let them draw, fold paper, cut and paste, strengthen handicraft skills, train children to use their hands and brains, further promote the development of brain function, and teach children to write some simple Chinese characters and Arabic numbers, pay attention to training children’s correct writing posture and pencil grip posture, so as to lay a good foundation for elementary school. Language development The child’s language development starts with spoken language. At the age of 3, the child can say his or her name, gender, age, and the names of the main family members. They can understand the meaning of hundreds of words and can use them to form simple sentences, such as “I want to drink water”, “I want to pee”, “I want to sleep”, “I want a car”, etc. I want to sleep”, “I want a small car”, etc. They can recognize several colors, identify some of the animal pictures, name several toys, distinguish how many, size, top and bottom, know the meaning of 1, 2 and 3, and sing a few children’s songs or recite a few short rhymes. By the age of 4, the ability to speak has improved significantly, and they can simply tell their parents what they have done with more correct grammar and more complete sentences. They can clearly express their requests, wishes and insights. Can recite 5 to 10 short poems (including ancient poems) and sing more children’s songs. Can say a few simple civilized and polite words, such as “hello”, “hello auntie”, “goodbye”, “thank you “. They can point to their sensory organs and tell the names and uses of them. They can know the names and uses of several household appliances, furniture and tableware, and can tell short stories like adults. At age 5, can understand the conversations of people around them and is willing to talk with them. They can tell their birthday, home and kindergarten addresses, and the occupations of their family members. Can name more objects, what they are used for and what materials they are made of. Can tell a story more completely and coherently after reading a children’s picture book. Can count through 1 to 100 numbers without interruption, and can recognize a larger number of words and pronounce them accurately. They can read aloud and recite simple literary works, recite 8 to 10 poems, and retell 3 to 4 stories they have heard others tell. By the age of 6 to 7, they are quite fluent in speech, can use vocabulary to express themselves, and can adjust the tone of their voice according to the content of their speech. They can listen to others politely and talk to others more comfortably. They have a preliminary ability to analyze things around them, and can tell stories after watching TV or movies. Recognize more words, some can recognize more than 100 words, and begin to practice writing.