This document discusses the theories and ideas of several prominent constructivist theorists including Jean Piaget, Jerome Bruner, Lev Vygotsky, John Dewey, and Maria Montessori. It summarizes their key ideas such as Piaget's stages of cognitive development, Bruner's emphasis on discovery learning and a spiral curriculum, Vygotsky's zone of proximal development and scaffolding, Dewey's progressive education approach, and Montessori's child-centered practical learning activities. The document advocates for active, participatory, collaborative, experience-based learning strategies based on the constructivist view that learning is constructed from one's experiences and interactions with others and the environment.