Comparative Effects of Two and Three Dimensional Techniques of Autocad on Spatial Ability, Interest and Achievement of National Diploma Students in Engineering Graphics.
ABSTRACT
This study was designed to determine the comparative effects of two and three-dimensional techniques of AutoCAD on National Diploma students’ spatial ability, interest, and achievement in engineering graphics.
The study was a pretest, posttest, non-equivalent control group quasi-experiment which involved groups of students in their intact classes assigned to treatment groups. Six research questions and nine hypotheses, tested at 0.05 level of significance, guided the study.
The population of the study consisted of 350 ND I mechanical engineering technology students in the polytechnics in the south-western geo-political zone of Nigeria.
The sample size was 227 students from which 108 students constituted treatment groups assigned to AutoCAD 2-D technique, and 119 students constituted another treatment group assigned to AutoCAD 3-D technique.
The instruments used for data collection were the Purdue Visualization of Rotation Test (PVRT), Engineering Graphics Achievement Test (EGAT), and Engineering Graphics Interest Inventory.
The Purdue Visualization of Rotation Test (PVRT) was adopted and had been validated by the test developer.
To ensure content validity of the EGAT, a Table of Specification was built for the test. The PVRT, EGAT, Engineering Graphics Interest Inventory, the AutoCAD 2-D and 3-D lesson plan, and the Training plans for the engineering graphics lecturers and students were subjected to face validation by five Experts.
The EGAT was trial tested for the purpose of determining the psychometric indices of the test. A total of 45 items of the EGAT had good difficulty, discrimination, and distractor indices. In addition to face validation, the engineering graphics Interest Inventory was also subjected to construct validation using factor analysis technique.
Out of 40 items, a total of 28 items were finally selected for the interest inventory. The reliability coefficient of the PVRT had been established by the test developer.
However, to account for varied cultural and social contexts, a trial test was carried out on the PVRT for determining its reliability coefficient. Split Half Reliability was computed to be .82 for samples of 39. The trial test for determining the coefficient of stability of the EGAT was carried out using the test re-test reliability technique.
Pearson Product Moment Correlation coefficient of the EGAT was found to be .80. Cronbach Alpha was used to determine the internal consistency of the Engineering Graphics Interest Inventory items. The reliability coefficient computed for the Engineering Graphics Interest inventory was found to be .91.
INTRODUCTION
Background Of Study
Computer-Aided Design (CAD) denotes the integrated use of computers in the conceptualization and design of products. According to Christopher (1990), Computer-Aided Design embraces the use of computers in the industry for design, simulation, and graphics design such as engineering graphics.
Engineering graphics is one of the core courses for students of the National Diploma in Mechanical Engineering Technology in Nigeria Polytechnics.
It involves the construction of different geometric figures and shapes, orthographic projections, the orientation of objects in space, developments of objects, and intersections of regular solids and planes (National Board for Technical Education (NBTE), 2003).
Spatial visualization is an established element of engineering graphics and is integral for success in graphics and engineering as a whole (Strong and Smith, 2002). Recent attention to spatial ability in engineering graphics, according to Basham (2007), is largely due to the vast changes in computer technology and CAD software packages.
Many application software packages have been developed for computer-aided design, well-known among the CAD packages available for graphics design in AutoCAD.
AutoCAD is an interactive drafting software package developed for the construction of objects on a graphics display screen. It is a vector graphics software developed in 1982 by Autodesk incorporation (Bui, 2006).
It uses primitive entities such as lines, polylines, circles, arcs, and text as the foundation for more complex objects (Wikipedia, 2007). According to Bui, AutoCAD is one of the most powerful CAD software which can perform nearly any graphics task. There are two techniques of graphics in the AutoCAD environment.
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