Constructivism is a theory of learning that explains how people might acquire knowledge and learn. It involves people constructing their own understanding and knowledge through experiences and reflecting on those experiences. Key figures in constructivism include Piaget, who described cognitive development in children through stages of learning; Bruner, who viewed learning as an active process of constructing new ideas; and Vygotsky, who emphasized social learning and the zone of proximal development. Constructivism encourages active learning, questioning, reflection, group work, and building on prior knowledge and experiences in the classroom.