Urie Bronfenbrenner's Bioecological Theory or Model of Human Behavior describes the interactions that affect a developing child. They can be negative and positive and it is the way the child reacts that links all the systems within his Model.
To understand how children develop, it is essential to understand how we use natural resources and the availability of them within the human environment
A child may have a favorite teacher at school and she is the motivation for him going every day. When she is absent, he may be less inclined to go and may need persuasion as he is directly influenced by her absence. This relationship falls within the micro system.
Within the mesosystem a child has relationships with friends for example and can be influenced by his peers. A child will behave one way around his friends and quite differently around his parents or teachers.
Women returning to work after having a baby who would like to continue breastfeeding can do so if the employer provides the facilities. A child can then directly benefit from continuing to be breastfed but he has no say in it or in the arrangement between his mother and her employer. This falls within the scope of the exosystem.
The macro system, as the name suggests, is the community at large: beliefs, customs and economic and social systems within a culture fall within its scope. A child living in the US will almost certainly have a completely different lifestyle to one living in Nigeria.
There are many factors at play in the development of the child.