The bridge between teaching and learning is different for each student, hence an assessment method is needed to gauge understanding. For Engineering Education, the assessment must be designed based on the Engineering Accreditation Council (EAC) requirements, which fulfills the Outcome-based education (OBE) learning approach. Rasch Model offers an approach that provides empirical evidence on each student's true ability with respect to the difficulty of the final examination questions. This paper explores the wonders of Rasch Model to assess the students' performance in the final examination, as well as the validity of the assessment instrument for a core course in Mechanical Engineering.