A number of assessment methods are used to improve teaching which accelerates students' achievement. This study investigates the effect of two assessment methods (Think - Pair - Share and Choral Response) on academic achievement of prospective science teachers in a public sector university in Lahore, Pakistan. It employed a quasi-experimental pretest-posttest control group design which was conducted on two already existing intact groups i.e. control group (n=51) and experimental group (n=36). The pre-test was administered to both the groups, and then the participants were exposed to the treatment after which the post-test was administered. The two tests, which had been devised based on Bloom's Taxonomy of Educational Objectives, were the same for both groups. The validity of the tests was ensured by five relevant experts; the reliability was established as 0.832 through a pilot study on 200 prospective teachers. Those items in the test were selected that had difficulty ratings of 0.2-0.8 and discrimination ratings of 0.2-0.6. The collected data were analysed using independent sample t-test. Results revealed that the students who were assessed through chosen methods of assessment showed better performance than those who were assessed traditionally. It was also found that students showed better performance while applying Think-Pair-Share than Choral Response. Hence, the study recommended to use these methods of assessment during teaching in order to improve students' achievement.