Physical development means growing in height, weight and body proportions. Parents and teachers are aware that children grow taller and heavier and stronger everyday. The growth in body is very rapid in early years, particularly from the birth to the age of two. Then the growth slows down till it again becomes rapid with the coming of puberty, the stage of maturity both in boys and girls.
Educationists and psychologists have studied that physical growth and development come under four distinct periods. Two a\re characterized by slow growth, while two other by rapid growth. These periods can be differentiated as follows:
1. The pre-natal period,
2. The Stage of Infancy and Babyhood, (0-2 years)
3. The Childhood-Early and Late Childhood, (2-6, 6-12 years)
4. The period of Adolescence, this leads to adulthood. (12-18 years)
The Prenatal period
This is the first developmental period in the life span of any individual. This period begins-at conception and ends at It is approximately 270 or 280 days in duration.
In other words, this period is nine calendar months or ten lunar months (one lunar month is said to be 28 days on average).This period of growth and development takes place in the body of the mother before the birth of the child.
The word-"natal" is an adjective connected with birth. Since the period of growth and development occurs before the child-birth, it is called prenatal development. During this pre-natal period the human organism passes through three general stages: Germinal, embryonic and fetal. The term germinal is applied to egg-like organization. This exists in the mother's womb for about two weeks after the union of female ovum with the male spermatozoon. This union, in the language of physiology, is called conception. In this union, the ovum is fertilized by millions or billions of cell divisions. After a continuous process of 270 or 280 days the new born baby comes out. By the 8th week of development it is known as embryonic stage. Now the structure displayed human characteristics.
From the 8th week to birth, the development is known as fetal stage. Now it is called human fetus. This has grown after the conception and now, continues to develop human structure and organs. After birth, the new born sees the light of the world and grows and develops into a human being. They start the post-natal period of the child.
It is really, a wonder, as to how this microscopic single cell ovum becomes a seven or eight pound baby with arms and legs, a large number of bones and all other internal complex organs. A one-celled fertilized ovum has a supply of nourishment and proceeds to grow and divide into two cells, four, and eight and so on, up to an enormous number of cells. All this descend from the same union of the male and female cells.
Stage of Infancy and Babyhood:
Infancy is the beginning or the early period of existence of the newborn. It is now a separate individual and not a parasitic- in the mother's body. Infancy is the shortest of all developmental periods. It begins with birth and continues till the infant is two-week old. During this period the infant makes adjustments to the new environment outside the mother's body.
The rapid growth and development which took place during the prenatal period, suddenly came to a stop with birth. There comes a halt in growth and development till it adjusts to the post-natal environment. It continues for a period of two weeks.
Once these adjustments have been made, infants again resume their growth and development. It is a fact that some infants are born prematurely. This means some children take birth before the scheduled period of time, while some others take birth post-maturely. So it is obvious that not all infants will show the same level of physical and mental development. Malnutrition of the mother during pregnancy has been found to be responsible for premature births and still births.
At birth, the average weight of an infant regardless of sex and race is 7 or 8 pounds. And the average height of an infanct is about 20.5 inches.
Of course, weight in relation to height is less, at birth. It is found that; boy infant is slightly longer and heavier than girls. With the birth cry, the lungs are inflated and respiration begins. The eyes of new born are almost mature in size. The nose is very small and almost flat on the face, while the tiny mouth may look like a slit if the lips are narrow. The neck is so small that it is almost invisible. The hands and feet of the infant child are miniatures.
At birth, the baby has no teeth and can suck only milk and water. As teeth appear, soft and solid food can be chewed and swallowed till he can break and digest hard nuts too. Although the infant's heart starts beating before birth, he breathes only after he is born. With breathing, circulation of blood increases.
At first, the infant's heart-beats are 140 per minute. Gradually they decrease to 100 and come to 72 for a normal adult. Changes also take place in nerves, muscles, bones and joints which become larger, stronger and firmer. Glands too change in their size and function.
In the process of growth and development, babyhood occupies the first two years of life following the brief two- week period of infancy. Babyhood is often referred to as infancy. But the only difference is that babyhood is distinguished from the extreme helplessness of infancy. This babyhood is the true foundation period of life of human beings. Also babyhood is a period rapid growth and change. Babies grow rapidly both physically and psychologically.
Babyhood is an age of decreasing dependency. In other words, rapid development of baby leads to decrease in dependency on others.
Babyhood is one of the two periods of rapid growth during the life span of human beings. The other period comes at puberty. The general pattern of growth and development is similar for all babies. There are variations in height, weight, sensory capacities and other areas of physical growth.
Some babies start life smaller in size and less developed than the normal. This may be due to prematurely or to a poor physical condition resulting from maternal malnutrition, stress and strain or some other unfavorable condition during the prenatal period. As a result, such babies tend to fall behind there age-mates during the baby-hood years.
The Childhood Stage
Most people think of childhood as a fairly long period in the life span of a human being. To children, childhood often seems endless they wait for the prestige time which the grownups enjoy in society.
Childhood begins when the relative dependency of babyhood is over. Approximately, this period extends from the age of two years to 12years. How ever the time when children become sexually mature, at the age of 13 years for the average girl and 14 years for the average boy. By the time the children become sexually mature, they are known as adolescents.
During long period of time-roughly 11 years for girls and 12 years for boys, marked changes take place in the child, both physically and psychologically. To-day it is widely recognized that childhood should be subdivided into two periods.—early and late childhood.
Growth during early childhood proceeds at a slow rate as compared with the rapid rate of growth in babyhood stage. Early childhood is a time of relatively even growth. Height, weight, body proportions, body build, bones and muscles grow to make the child ready for adulthood.
Early childhood extends from 2 to 6 years of age and late childhood extends from 6 to 13 or 14 years of age. Thus the early childhood begins at the conclusion of babyhood. It is the school-entrance age. There is relatively little difference in the physical growth and development of children before and after they are six years old. Radically it makes little difference between five-year-old and seven-year old children.
Late childhood is also called stage of pre-adolescence. The development of the child at this stage depends on his motor development. By motor development, it is meant the development of strength, speed and precision in the use of one's arms, legs and other body muscles. It is important because it has great bearing on child's emotional, intellectual and social development. Motor development takes place at a rapid pace during childhood. Motor skills develop in the child from more generalized to more specialized form of activities. At this stage, some left-handed could be made right-handed.
The Period of Adolescence
It cannot be said with accuracy as a when adolescence sets in. This is the period of maturity. Generally, it is described that the teen-agers are the adolescents. It is the most critical stage in the life span of human beings. The boy of fourteen is characterized as "neither useful nor ornamental." This is the period of maturity. It is told that maturity marks the end of growth. Growth of any organism from an immature to a mature state is called maturation.
In this period, child's legs and other muscles grow to size and strength sufficient for standing, talking and running to the maximum. His hands grow into excellent instruments for manipulating objects. His teeth already present in rudimentary form grow for harder work. His mouth and larynx grow into flexible speech organs. His brain grows not only in size, but also in fineness to capably do its share in all human activities.
Sexual maturity also is reached by this age of adolescence, while many animals reach maturity in a few weeks or months after being born; it takes human beings about 18 to 20 years. And during all these years he is maturing and learning, what he is as an adult always depends on how well he has grown. There are really great physical developments at this stage.