Conventional graded assignments are commonly structured in a format where students attempt a prescribed question and are graded based on the completeness of their workings rather than the understanding of concepts. An alternative assignment format was proposed which requires students to identify and explain mistakes in a given set of workings based on a question. Questionnaire responses from 243 civil engineering undergraduates from National University of Singapore showed that majority preferred this format. They also felt that it enhanced their learning and thinking ability. However, based on results, students fared better in the conventional format due to its familiarity. Furthermore, students were generally over-optimistic about their grades. A possible reason could be the misinterpretation of the requirements of the alternative format. As such, role play was introduced to clarify concerns raised by students. Analysis also showed that students who are academically inclined reaped greater benefits from the new approach as compared to students who are not as strong academically.