In what year was constructivism introduced?

Constructivism as a theory of learning and development emerged in the early 20th century, with key contributions from psychologists like Jean Piaget and Lev Vygotsky. While Piaget's work began in the 1920s, constructivist ideas gained prominence in educational theory throughout the 1960s and 1970s. Thus, while there isn't a single year of introduction, the foundational ideas of constructivism were established in the early to mid-20th century.