Constructivism is a learning theory where learners actively construct knowledge by interacting with their environment and experiences. There are two main types - social constructivism focuses on culturally and socially influenced learning through collaboration, while cognitive constructivism emphasizes individual perception and exploration. Constructivist teaching approaches view learning as an active process where students build upon a foundation laid by teachers to gain understanding in a meaningful context. The role of the teacher is as a guide facilitating a student-centered, multimedia curriculum that considers multiple intelligences and learning styles.