Constructivism is a theory of learning that argues humans construct new knowledge from their experiences. Key people associated with constructivism include Piaget, Dewey, Vygotsky, and Bruner. Piaget identified four stages of cognitive development. Vygotsky believed learning occurs through social interaction and defined the zone of proximal development. Bruner emphasized instruction should relate to students' experiences and allow them to build on prior knowledge. According to constructivism, students learn by actively participating in experiments and discussions rather than passive learning.