An Evaluation of The Relationship between Spatial Skills and Creating a Free Body Diagram

Spatial visualization is the ability to imagine what an object looks like from various viewpoints or after the object has been rotated in space or transformed in another way by some amount. Numerous studies have shown the link between spatial skills and success in engineering. But how do well-developed spatial skills contribute to engineering student success? In previous studies with elementary students, children with good spatial skills were able to create strategic sketches-sketches that accurately represented the problem and led to a correct answer. Poor visualizers drew non-strategic sketches-these were pictorial in style and did not lead to correct solutions. For example, when asked how many trees could be planted along a driveway that was 15 meters long if they were spaced every 5 meters, high visualizers drew a plan view of a line with an X spaced every 5 meters to arrive at the correct answer. Low visualizers drew a picture of a tree. In this paper, we report on a study to examine the link between spatial skills and the ability to solve problems from engineering mechanics. A total of 128 students from upper division engineering courses completed several tests of spatial skills and were also asked to solve 6 engineering mechanics problems. One of the six problems was merely to draw a free body diagram of a crane. In this paper, we examine the quality of the free body diagrams made by students to measure accuracy of the sketch, appropriateness of schematic representation and number and type of errors. How each of these factors relates to spatial ability will be reported along with examples of student work. This paper will illustrate the variation in approach to constructing free-body diagrams among students with low and high levels of spatial ability.