Abstract: Constructivism is buzz word widely used in paradigm of teaching-learning. Constructivism emphasises how the learner constructs knowledge from experience, which is unique to each individual. In the present paper the areas of discussion are 1) historical background of constructivism and its importance. 2) Role of mentor and learner in constructivist science classroom. 3) An attempt is made to prepare a lesson plan for science teachers based on 5E’s model (one of the model of constructivism) on the topic ‘Images formed by concave lenses’. This sample lesson plan will facilitate the science teachers in the implementation of constructivism in their classroom.