Child development

Child development involves the biological, psychological and emotional changes that occur in human beings between birth and the conclusion of adolescence. It is—particularly from birth to five years— a foundation for a prosperous and sustainable society.

Childhood is divided into three stages of life which include early childhood, middle childhood, and late childhood (preadolescence). Early childhood typically ranges from infancy to the age of 6 years old. During this period, development is significant, as many of life's milestones happen during this time period such as first words, learning to crawl, and learning to walk. Middle childhood/preadolescence or ages 6–12 universally mark a distinctive period between major developmental transition points. Adolescence often occurring around the onset of puberty, marked such as menarche and spermarche, occurring between 12 and 14 years of age, and ending during the mid-20s characterized by maturation of the body, intensification of capacity for learning, and emergence of personal identity. Developmental change may occur as a result of genetically controlled processes, known as maturation, or environmental factors and learning, but most commonly involves an interaction between the two. Development may also occur as a result of human nature and of human ability to learn from the environment.

There are various definitions of the periods in a child's development, since each period is a continuum with individual differences regarding starting and ending. Some age-related development periods with defined intervals include: newborn (ages 0 – 2 months); infant (ages 3 – 11 months); toddler (ages 1 – 2 years); preschooler (ages 3 – 4 years); school-aged child (ages 5 – 12 years); teens (ages 13 – 19 years); adolescence (ages 10 - 25 years); college age (ages 18 - 25 years).

Parents play a large role in a child's activities, socialization, and development; having multiple parents can add stability to a child's life and therefore encourage healthy development. A parent-child relationship with a stable foundation creates room for a child to feel both supported and safe. This environment established to express emotions is a building block that leads to children effectively regulating emotions and furthering their development. Another influential factor in children's development is the quality of their care. Child-care programs may be beneficial for childhood development such as learning capabilities and social skills.

The optimal development of children is considered vital to society and it is important to understand the social, cognitive, emotional, and educational development of children. Increased research and interest in this field has resulted in new theories and strategies, especially with regard to practices that promote development within the school systems. Some theories seek to describe a sequence of states that compose child development.

Also called "development in context" or "human ecology" theory, ecological systems theory was originally formulated by Urie Bronfenbrenner. It specifies four types of nested environmental systems, with bi-directional influences within and between the systems; they are the microsystem, mesosystem, exosystem, and macrosystem. Each system contains roles, norms, and rules that can powerfully shape development. Since its publication in 1979, Bronfenbrenner's major statement of this theory, The Ecology of Human Development, has had widespread influence on the way psychologists and others approach the study of human beings and their environments. As a result of this influential conceptualization of development, these environments – from the family to economic and political structures – have come to be viewed as part of the life course from childhood through adulthood.

Jean Piaget was a Swiss scholar who began his studies in intellectual development in the 1920s. Interested in the ways animals adapt to their environments, his first scientific article was published when he was 10 years old, and he pursued a Ph.D. in zoology, where he became interested in epistemology. Epistemology branches off from philosophy and deals with the origin of knowledge, which Piaget believed came from Psychology. After travelling to Paris, he began working on the first "standardized intelligence test" at Alfred Binet laboratories, which influenced his career greatly. During this intelligence testing he began developing a profound interest in the way children's intellectualism works. As a result, he developed his own laboratory, where he spent years recording children's intellectual growth and attempting to find out how children develop through various stages of thinking. This led Piaget to develop four important stages of cognitive development: sensorimotor stage (birth to age 2), preoperational stage (age 2 to 7), concrete-operational stage (ages 7 to 12), and formal-operational stage (ages 11 to 12, and thereafter). Piaget concluded that adaption to an environment (behaviour) is managed through schemas and adaption occurs through assimilation and accommodation.

Sensory Motor: (birth to about age 2)