Constructivism is a learning theory based on the idea that learning occurs through active construction of knowledge rather than passive reception of information. According to constructivism, learners build new knowledge upon the foundation of previous learning. Key aspects of constructivism include collaborative learning, scaffolding of instruction, and the zone of proximal development. Major theorists who contributed to constructivism include Piaget, Bruner, Vygotsky, and Dewey. Constructivist classrooms emphasize active learning, collaboration, exploration of real-world problems, and use of technology to facilitate learning.