Abstract:
This study was designed to determine 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 groups assigned to AutoCAD 3-D technique. The instruments used for data collection were 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 context, 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 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. The data collected were analyzed using Mean, to answer the research questions while ANCOVA was used to test the nine hypotheses formulated to guide this study. The study found out that AutoCAD 3-D technique is more effective in improving students’ achievement, spatial ability and interest in engineering graphics than AutoCAD 2-D technique. There was a significant effect of Gender on students’ spatial ability and achievement in engineering graphics favouring boys. The study found out no significant interaction effects of AutoCAD techniques and gender on spatial ability, achievement and interest of National Diploma students in engineering graphics. Hence, irrespective of nature of gender, learners will record improved performance in their spatial ability, interest and achievement in engineering graphics when AutoCAD 3-D technique is employed for teaching engineering graphics. Consequently, it was recommended that (1). Technical teachers teaching engineering graphics should adopt the use of AutoCAD 3-D technique to teach engineering graphics; and prepare their lessons in such a way
