| Popis: |
The focus of the present research is on children's understanding and use of data bases. Previous research in this area is limited and has been mainly machine-centered. Some studies have been done to analyse the effectiveness of data bases compared to more traditional methods (paper and pencil) in information handling activities; and some others have focused on the comparison among several data base systems in order to see to what extent the system characteristics (data base structures - command/menu driven systems) influence the process of information retrieval. However very little attention has been paid to the process of teaching and learning data bases, to the nature and structure of data base tasks, and the factors that affect students' performance on such data base tasks. This latter perspective, task-centered, is the one taken by the present research. The present research investigates the possible existence of a theoretically proposed five-level hierarchy of data base tasks. 13 and 16 year old students' performance on two different types of data base tasks using GRASS is examined. The research also involves questions about the skills and knowledge that students possess and which affect the quality of data base interrogation activity, such as understanding of the nature of data bases, understanding of the nature of data base search and structure. and understanding of Boolean logic in the phrasing of complex queries. Children were tested on a range of such tasks before and after being trained in the use of GRASS. The results show that children at 13 and 16 can perform simple data base operations and tasks rather successfully. There is some hierarchy in the difficulty of tasks, but not precisely that proposed theoretically. Tasks involving two variables, and relations between them, are relatively difficult, particularly for the younger group. Tasks requiring simple retrieval and sorting data are the easiest. Logical operations present difficulties, especially in the construction of logical sentences, with simple AND combinations being the easiest. OR is sometimes treated as AND, particularly when interpreting negative OR propositions. Contradictions and tautologies are very difficult both to interpret and construct. Children seem to have an adequate if simple model of a data base in terms of the types of information a data base can and can not contain. However, their models of the ways information is kept, organised and found in a data base are not so adequate. |
