This chapter expands on the key principles of the constructivist approach to learning, including the role of the learner and the teacher as a mediator. It introduces Piaget and Vygotsky, the leading theorists who shaped this approach, and highlights the essential need to understand and construct knowledge through the learner’s experience. The current chapter presents models of five lessons—in the disciplines of history, science, literature, music, and geography—that have been implemented and tested by pre-service teachers in their classrooms, offering practical insights for effective lesson planning and idea generation.