Constructivism is a learning theory that posits that people actively construct their own understanding and knowledge of the world through experiences and reflecting on those experiences. There are two main types: social constructivism which views knowledge as constructed through social interactions and psychological constructivism which sees individual learning and understanding as constructed through personal experiences. Key proponents of constructivism include Dewey, Piaget, Vygotsky, and Kant. Constructivist classrooms value student-centered learning, collaboration, and using student questions and perspectives to shape instruction. Assessment is incorporated into the learning process through observations and student performances rather than separate tests.