Final answer:
Social change occurs through significant shifts in technology, social institutions, population, and the environment. Industrialization and the resulting urbanization led to smaller average family sizes. The 1920s in the U.S. illustrated social change through technological advancements, economic shifts, and cultural changes.
Step-by-step explanation:
Social change would be said to have occurred in scenarios where there have been significant shifts in aspects such as technology, social institutions, population, and the environment. For example, the industrialization that took place during the end of the 1800s altered society by reducing the need for large families who formerly engaged in manual labor on farms, consequently leading to smaller family sizes due to new job opportunities in urban areas. Moreover, the 1920s in the United States exemplified social change through various ways: the rise of new technologies, changes in economic policies, and shifts in cultural norms and political ideologies.
Social movements, such as environmental advocacy groups or civil rights organizations, also drive social change by organizing purposeful efforts to enact reforms or grant political voice to the underrepresented. The decrease in average family size as a result of urbanization and the shift from agriculture to industrial labor is an example of how a change in one social institution can impact others.