The mesosystem refers to the point in which two social microsystems merge. One example of a mesosystem is the combination of the home and school environments. These intersect and become a mesosystem when events, situations, work and friendships cross back and forth between both environments.
Microsystems are part of the social environments that people encounter during various stages of their life. The mesosystems that occur when various aspects of a person's life intersect are valuable to learning and adapting. Consequently, it is important to note that these crossovers occur at most frequently during childhood, thus impacting a child's social development.
When a child goes from their parents' home to spend the weekend with their grandparents, they have a different set of values and disciplines to adhere to from their normal home environment. These changes in expectations and requirements teach a child how to adapt and fit into new systems or situations. In this situation, the child learns that adhering to their grandparents' expectations while visiting with them will get the child rewarded and praised, whereas the same actions may not result in similar praise when at home, as the expectations there may be different.
Even within a larger microsystem, such as school, there can be smaller microsystems, which result in their own mesosystems. These occur frequently as students interact with different areas within their environment. An example would be when a child leaves their English class and goes to their math class. This is a different micro group of friends and a teacher with different expectations, so their actions must change accordingly.