Abstract:

Frequently, instructors find that many of their students perform well in exams that involve solving problems similar to those assigned in class, but are unable to give proper explanations to basic concepts or solve problems that involve the same ideas in different contexts. On the surface, this observation can be explained by assuming that students are just memorizing the contents required to pass the exam. However, extensive research [1] has shown that new physical concepts are actually hard to assimilate because of a variety of reasons:
(1) every person has intuitive mental models on how the physical world works,
(2) these models use to provide satisfactory explanations in everyday contexts, but are often incompatible with the accepted scientific thought, and
(3) some of these naïve models can be extremely difficult to change by means of formal instruction.

Considering this, what we see in many of our students is that they apply a set of rules to solve classroom problems but continue to use their old ideas in “real world” contexts. The new ideas presented in class are not actually assimilated because they are in conflict with previously well-established beliefs.

Several authors have published well developed diagnostic tests that allow to identify major misconceptions in several fields of physical science, for example Newtonian Mechanics [2], Thermodynamics and Heat Transfer [3] or Fluid Mechanics [4]. These tests usually consist of several tens of questions that present everyday situations, not “standard classroom” situations, asking the student to select the best explanation from a set of possible responses. The wrong responses are typical conceptual errors, and sometimes mere distractors.

In this paper, we present the results of applying a test, based on the test developed by Martin et al. [4], to 160 students of three engineering degrees at the Polytechnic School of Malaga (Spain): Mechanical, Electrical and Electronic Engineering. The test was uploaded to Moodle and administered to our students both before and after instruction. Because students had no previous training in Fluid Mechanics, the pre-course test was a reduced version of the complete test, with selected questions that did not involve elaborate concepts. The results of these tests are analysed and discussed in this paper. Questions are classified by topic (properties of fluids, hydrostatics, external flow, etc.), and pre and post course scores are calculated for each topic. The percentage of gain in understanding the basic concepts is also calculated by comparing both tests. These results give insight into the level of understanding of the basic concepts of Fluid Mechanics by the students of a typical technical school, and provide useful feedback to the instructor, who gets a diagnosis at the beginning of the course and a measure of success after the course.

References:
[1] Bain, K. (2004). What the Best College Teachers Do. Harvard University Press
[2] Hestenes D., Wells M, Swackhamer G. (1992). Force Concept Inventory. The Physics Teacher 30, pp. 141-158.
[3] Yeo S., Zanik M. (2001). Introductory Thermal Concept Evaluation: Assessing Student’s Understanding. The Physics Teacher 39, pp. 496-504
[4] Martin J., Mitchell J., Newell T. (2003). Developed of a Concept Inventory for Fluid Mechanics. 33rd ASEE/IEEE Frontiers in Education Conference, Nov. 5-3 2003, Boulder (CO), pp T3D-23,T3D-28

Keywords:

Misconceptions, Concept Inventory, Fluid Mechanics.