The general pattern of growth and development of elementary school students refers to the general phenomenon that most elementary school students exhibit during their growth process. Although genetic, environmental, nutritional, physical exercise, disease and other factors can lead to inter-individual differences, but the general rule still exists universally. The growth and development process of children and adolescents in China is staged as follows: infancy, from birth to 1 year old; early childhood, l to 3 years old; preschool, 3 to 6 years old; school age, 7 to 11 or 12 years old; adolescence, about 10 to 20 years old.
First, growth and development is the process from quantitative to qualitative change
The growth and development of elementary school students, not only is the height and weight increase, but also the whole body organs are gradually differentiated, and gradually matured functions. Although the quantitative and qualitative changes have a certain stage of urgency, but the two often alternate. For example, during the process from infancy to adolescence, the length of the digestive system and the volume of the stomach increase significantly, and its structure and function are gradually improved. The content of various digestive enzymes increases, the secretion of gastric acid increases and its concentration rises, and the digestive system gradually reaches the ability to digest complex solid foods from only a small amount of liquid food. Another example is the brain in the process of gradually increasing in size and weight, its cortical memory, thinking, analysis and other functions are also developing, and after the brain grows in size and weight, its functions are still developing and perfecting.
Second, the unevenness and program of growth and development
People always grow and develop continuously from childhood to adulthood, with both continuity and stages. Each stage has its own characteristics, different from other stages, and at the same time, each stage alternates and connects with each other in a regular manner.
(I) The first growth spurt
The first growth spurt starts from the fetal period to 1 year after birth. In terms of height and weight, for example, the height increases by 20-25 cm and the weight increases by 6,000-7,000 g during the first year. In the second year, height increases about 10 cm, weight increases about 2 500 ~ 3500 grams, is the stage of faster growth rate after birth. Thereafter, the growth rate decreases significantly, with height increasing by about 4 to 5 cm per year and weight increasing by about 1,500 to 2,500 grams per year until about 10 years of age.
(B) The second growth spurt
Girls about 10 to 12 years old, boys about 12 ~ 14 years old into the second growth spurt, that is, the puberty development period. An important feature of this period is that the age of growth and development of girls is generally about two years earlier than that of boys. 10 years old before, the physical differences between boys and girls is small, boys are slightly higher than girls. 10 years old after the average number of girls regardless of height, weight, etc. are higher than boys, forming the first cross on the development curve; about 12 years old boys began to develop, about 14 years old boys height, weight and more than girls; the formation of the second cross on the development curve. The second crossover on the development curve. Since then, the values of the indicators of boys have been higher than those of girls, eventually forming a significant difference between men and women in terms of height and weight.
Third, the procedures and laws of growth and development of various parts of the human body
Although the growth and development of various parts of the human body is not balanced, but in accordance with the procedure follows a certain pattern. For example, in the two peaks of growth and development, the body parts develop in different proportions. During the first peak, the head grows first, and then the limbs grow, and the head circumference is about 34 cm at birth, about 46 cm at 12 months of age, and 48 cm at 24 months of age. Thus, the head circumference of the child increases by 12 cm in the first year, only 2 cm in the second year, and only 6-7 cm in total from the age of 2 until the age of 14. This is the pattern of cephalocaudal development. The second peak of head growth is not obvious, but the lower limbs develop rapidly.
From the age of 7, the growth and development of the human body follows a centripetal rhythm. The procedure of the development of its parts is: foot and lower leg, lower limb, hand and upper limb, that is, from the bottom up, from the distal end of the limbs to the trunk, so called “centripetal rhythm”. Biomechanical analysis of the developmental sequence is also consistent with the centripetal law. The order of human activity and total load is: foot – calf – thigh – hand – arm – trunk – head. According to the law of unity of form and function, the greatest amount and intensity of load is on the lower extremities, followed by the upper extremities and trunk, and the centripetal rhythm is precisely adapted to the needs of the above functions. During the whole growth and development process, the proportion of human body parts, from a large head (about 1/2 of height), longer trunk and short lower limbs in fetus, develops into a smaller head (about l/8 of height), shorter trunk and longer lower limbs in adult. During development from birth to adulthood, the head grows by a factor of 1, the trunk by a factor of 2, the upper limbs by a factor of 3, and the lower limbs by a factor of 4.
The development of the body systems is also uneven. First, the nervous system, especially the brain, is the first to develop after birth, and thereafter it is always developing and improving in structure and function until maturity. The development of other body systems such as motor, respiratory, digestive, and urinary systems is similar to the development of height and weight in a wave pattern. The development of the lymphatic system peaks around the age of ten and gradually decreases thereafter, which indicates that elementary school students have acquired considerable immunity around the age of ten.
From the above, we can see that although there are sequential periods of development of various body parts and systems, the order of development of each system is connected to each other and closely related, always the development of the former stage lays the foundation for the latter stage.
Fourth, there is a long-term trend of accelerated growth and development
Since the 19th century, scholars in Europe and the United States have found from a comparison of one or two hundred years of data on growth and development that elementary school students in industrially developed countries have increased in height from one generation to the next. The increase is even more pronounced in those who have better living conditions. Studies show that the average height of the current lower elementary school students increased by 5-10 cm compared to the early 20th century. This long-term acceleration is also manifested in other aspects of growth and development, such as increases in head circumference, chest circumference, hip circumference, hand length, foot length, and other indicators.
A survey of elementary school students’ growth and development in China from 1978 to 1980 showed that the 7-14 age group grew by an average of 2.3 cm for boys and 2.1 cm for girls every 10 years. The long-term trend of accelerated growth and development is a profound change in the organization of the entire human organism. There are many factors contributing to the acceleration phenomenon, such as good nutrition, rich cultural and recreational life, sports, control of various infectious diseases, and the spread of knowledge about group hygiene. Nevertheless, this accelerating trend cannot continue forever, and there is bound to be a limit.
V. Growth and development include both physical and psychological aspects
The physical development and psychological development of elementary school students are unified, and the two are inseparable, influencing each other and complementing each other. The development of various systems, especially the development of the nervous system, laid the material foundation for the psychological development of elementary school students, while the normal development of the psyche can also ensure and promote the normal development of the body of elementary school students. Certain physiological defects can cause abnormal psychological development of elementary school students. For example, students with strabismus are often ridiculed by their classmates if they are not treated in a timely manner, which can lead to low self-esteem. The emotions of elementary school students are related to their state. Students who are consistently emotionally normal often hold their chests and heads up, sit, stand, and walk with correct posture, are mentally alert, and move quickly.
Actively participate in various school activities and can complete tasks well; on the contrary, students who have been emotionally depressed for a long time often also have a sickly appearance, stooping, hunchbacked, slow in action, depressed and inattentive. In recent years, foreign studies have shown that children of broken families and children born out of wedlock suffer from abuse and discrimination, which affects normal growth and development, and can seriously lead to short stature, backward bone age, delayed sexual development, and become psychosocial dwarfs. This may be the result of long-term malignant stimulation of the central nervous system by the adverse psychological environment.