Child development and dating
Some age-related development periods and examples of defined intervals are: newborn (ages 0–4 weeks); infant (ages 4 weeks – 1 year); toddler (ages 1–2 years); preschooler (ages 3–5 years); school-aged child (ages 6–12 years); adolescent (ages 13–19).
Another influential factor in a child's development is the quality of their care.
There are also some theories that seek to describe a sequence of states that compose child development.
Concrete: (about first grade to early adolescence) During this stage, children between the age of 7 and 11 use appropriate logic to develop cognitive operations and begin applying this new thinking to different events they may encounter.
Unlike the preoperational stage, children can now change and rearrange mental images and symbols to form a logical thought, an example of this is reversibility in which the child now has the ability to reverse an action just by doing the opposite.
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.