Need help with my writing homework on Childcare and Child Development in the Home Based Setting. Write a 1500 word paper answering; This period is characterized by interactions with the environment based on the child’s reception of sensory input and muscular reactions. The task of this period is to develop the concept of object permanence, the idea that objects exist even when they cannot be seen or heard. (Brewer, 2001). The Preoperational Period (two to seven years) marks the time when a child becomes able to represent objects and knowledge through imitation, symbolic play, drawing, mental images and spoken language. Lack of conservation skills is also characteristic of this stage. “Conservation is defined as the knowledge that the number, mass, area, length, weight, and volume of objects are not changed by physically rearranging the objects.” (Brewer, 2001) The ages of seven to eleven or twelve years fall under the Concrete Operational Period. Primary school children at this age begin to think more operationally. Piaget and Inhelder (1969) described the operational thinker as one who employs “identity or reversibility by inversion or reciprocity” (p.99) in solving problems. They have moved on from being egocentric and consider that others may come to conclusions that differ from theirs. The Formal Operational Period commences at age 12 and continues on to&nbsp.adulthood.&nbsp. This final stage of cognitive development is characterized by the ability to think abstractly, reason logically and draw conclusions from available data.&nbsp.