The chronosystem is the part of Bronfenbrenner's ecological systems theory that includes the events that transpire in a person's life. It is the final tier of Bronfenbrenner's ecological system, according to Education Portal.
Bronfenbrenner's ecological systems theory is an attempt to explain how children grow and develop. It is made up of steadily larger groups of influence, ultimately culminating with all the experiences of a child's entire lifetime.
At the smallest, closest level is the microsystem. This is the most immediate and direct influence on the child's development, and includes such factors as family, school, religious institutions, neighbors and peers.
Beyond that is the mesosystem. This represents the influence of two microsystems interacting. This can include such things as friends interacting with parents, parents interacting with teachers, teachers interacting with friends and so on.
After that is the exosystem. This is the environmental settings that a child is not actively involved in, but is influenced by. An example would be a parent getting a promotion that rewards him with higher pay, but involves longer work hours.
The macrosystem is next and serves as the overall definition of the child's culture. This includes the political and social beliefs of the culture, defined by being part of a group with a common heritage or identity.
Lastly is the chronosystem. This system includes major life transitions, environmental events and historical events that occur during development. The specific incidents tend to change or transition how the child interacts with all the rest. Moving to another city is one example, as is the first moon landing being televised.