The basic systems within Bronfenbrenner's Bioecological Model of Human Development are intertwined and reliant on each other in order to function correctly. However each does have its own role to play.
To understand how children develop, it is essential to understand how we use natural resources and the availability of them within the human environment.
There are many contexts in which children develop - home, school, community and so on and these span out to include a wider scope encompassing cultural and historical patterns that may affect human behavior.
The micro system is direct and immediate and involves face-to-face relationships and two-way communication within a single environment. A baby, for example changes the new parents' lives and their attitude affects their new baby.
The meso- system is essentially the interaction of at least two microsystems. This would often be the link say between home and school, peers and church groups a child may want to be a part of and is a useful tool in identifying children's actions in different settings such as his ability to communicate effectively at home but not speak up in class.
The exo-system is also concerned with at least two settings but, unlike the meso-system the child is not instrumental in both. A child will obviously be affected by his mother's choice of workplace but he has no influence over it. Parents choose the religion of their children, the schools children attend, their (the parents')voting preferences, etc.
The macrosystem is not related to an individual but more to his cultural and social environment. Family values and customs and any dominant beliefs and ideologies influence such things as family groups and by way of example whether a child grows up within a large extended family network.
Bronfenbrenner did add another system - the chronosystem- which involves the passing of time in cycles and major events .
According to Bronfenbrenner, a person shapes as well as experiences his or her own development and the different influences act and interact to contribute and form a complete person.
A Child's World 10th Ed. McGraw Hill