The present study investigated the effectiveness of constructivist approach on academic achievement in science at secondary level using pre-test, post-test, experimental and control group design, with 58 samples grouped as experimental group (29) and control group (29) on the basis of matching by intelligence test. The investigators conducted this experiment over three weeks by using both traditional and constructivist 7E-model. The self-developed achievement test covering Class IX Textbook of West Bengal Board of Secondary Education, India was used as tool. The study found that the students exposed to the constructivist 7E-model significantly achieved better than traditional method. In addition, students exposed to the 7E-model performed significantly higher than those exposed to the traditional teaching method in respect of their gained scores at every intelligence levels. The constructivist approach strategy is capable of improving student's mastery of content at the higher order levels of cognition. It is therefore recommended that constructivist 7E-model strategy be used in science teaching for the development of student's higher achievement in science at secondary level.