Back to freshman year of the BSW!
A 'system' is a group of parts that together make up a whole of something. Like our organs and tissue are parts that make up our bodies. In the same way, individual people, families, and organizations together make systems.
A key part of systems is the boundary. Boundaries are the outside of the system. For example, one could see my husband and I as a system. Together we are a married couple. You could also expand this system to include any children we may have (we just have cats, but you get the idea) and us and our children would make up another system. Or you could go out even further to encompass our parents and our sisters and brothers. Systems can also include our schools, our places of work, our communities, etc.
A 'closed' system is a system that has impassible boundaries. Open systems have boundaries that are flexible. Systems can be too closed or too open. For example, a couple with children who allows random strangers to sleep in their home has created a system that is so open it is dangerous. A less extreme example could be boundaries between children and parents that are so loose they act more as peers than parents and children. A family system that is too closed leads to isolation.
Organizational systems can also be open or closed. Personally, I've observed a support group that ignored new and inquiring members. This system (the support group) was supposed to be open, but the members maintained a closed group.
The book I am working from cites ecological levels of systems.
"Microsystem: situations in which the person has face to face contact with influential others.
Examples: family, school, workplace, church...
mesosystem: relationships between microsystems; the connections between situations.
Examples: home-school, home-workplace, home-church...
Exosystem: settings in which the person does not participate but in which significant decisions are made affecting the person or others who interact directly with the person.
Examples: ... school board, local government...
Macrosystem: 'blueprints' for defining and organizing the institutional life of the society
Examples: ideology, social policy, shared assumptions about human nature..." p. 66
In a nutshell, intervention using the systems theory would take into account outside forces on the person. Family needs, the neighborhood, factories leaving the state, and the state of the economy all impact a person's employment status. A student who is not fed at home is not going to excel in school despite any in-school interventions that may be made.
Ambrosino, R., Herrfernan, J., Shuttlesworth, G., & Amrosino R. Social work and social welfare: An introduction. (4th ed.) Belmont: Brooks/Cole.