This paper is a report of a study whose major purpose was to develop and validate a General Science Aptitude Test (GSAT) for Junior Secondary School graduate seeking admission into senior secondary school one in Nigeria. The specific objectives were to describe the various stages in the development and validation of GSAT and also to determine the psychometric properties of the instrument. The Pearson Product Moment Correlation, Test difficult index, discriminative index and the KuderRichardson 21 statistics were used for the analysis of results. The results of analysis show that the GSAT was moderately difficult for the sampled students (average item difficult is 0.39), while the instrument was found to be reliable since internal consistency was found to be 0.90. The inter-correlation among the GSAT‘s sub-scales was found to be substantial .GSAT is recommended for use in other parts of the world. Introduction There is a strong agreement among educationist and psychologist on the utility of aptitude tests in the process of educational and vocational decisions, about placement, streaming, admission and classification of students and job seekers (Gay, 1980; Macklem, 1990). According to Gay (1980), aptitude tests help the teacher to test more realistic expectations of students’ abilities and facilitate the identification of under achievers. The terms intelligence, ability, and aptitude are often used interchangeably to refer to behaviour that is used to predict future learning or performance. However, subtle differences exist between the terms. The tests designed to measure these attributes differ in several significant ways. Like intelligence tests, aptitude tests measure a student's overall performance across a broad range of mental capabilities. But aptitude tests also often include items which measure more specialized abilities such as verbal and numerical skills--that predict scholastic performance in educational programs. Compared to achievement tests, aptitude tests cover a broader area and look at a wider range of experiences. Achievement tests tend to measure recent learning and are closely tied to particular school subjects. Aptitude tests tell us what a student brings to the task regardless of the specific curriculum that the student has already experienced. The difference between aptitude and achievement tests is sometimes a matter of degree. Some aptitude and
Ariyo, Akinyele Oyetunde
achievement tests look a lot alike. In fact, the higher a student goes in levels of education, the more the content of aptitude tests resembles achievement tests. This is because the knowledge that a student has already accumulated is a good predictor of success at advanced levels. In literature there is no single definition of aptitude. Some investigators defined aptitude as the characteristics of a person that are regarded as indices of his capacity to acquire, through future training some specific set of responses (Aiken, 1988; Gronlund, 1981). On the contrary some other investigators see it as natural or innate capacity for a particular performance (Yejide, 1973; Thorndike & Hagen, 1977). Aptitude tests are cognitive (intellectual) measures used to predict future performance in some activities such as school learning and other forms of accomplishment (Aiken, 1988; Gronlund, 1981; Sax, 1980). Aptitude tests are widely used in schools and industries. Teachers might want to administer aptitude test to help them identify students who have potential to perform well in physics in the future so that they could be offered physics instruction. This is in line with previous...