Developing FD-MT to investigate students' mental model on fluid dynamic concept: a Rasch model analysis

Fluid dynamics has some complex and unobservable concept, however, tests are rarely developed to measure students' understanding of these concepts. This condtion make a difficulty to map students' mental models with existing instruments. Based on that problem, this study aims to develop FD-MT (fluid dynamic-multi tier test) as a diagnostic test for measure students' mental model on fluid dynamic concept. The ADDIE (Analyzing, Designing, Developing, Implementing, Evaluating) is a research method that used in this study. The data were collected by FD-MT will be analyzed by rasch model analysis, include the reliability, the validity, item fit and the differential item function. Student mental model clasified as Scientific, Synthesis-A (Sy-A), Synthesis-B(Sy-B), Syinthesis-C (Sy-C), Synthesis-D(Sy-D), and Initial. The participant of this study are 20 students in the eleventh grade (9 boys and 11 girls, 16-17 age in average) at high school in Bandung. Based on result study shows that students' mental model mostly in mental Sc (8.18%), Sy-A (3.18%), Sy-B (21.36%), Sy-C (19.09%), Sy-D (38.18%) and In (10%), and incompleted answer (Nr = 0%). This conclude that, FD-MT is able to measureing students' mental model on fluid dynamic concept.