Abstract:

Databases are significant in the academic training of computer science engineers since most of the modern software systems need them to work adequately. Inside the database area, it is essential that any student knows the design process, which involves the creation of both the entity - relationship and the relational model. The former is a conceptual representation, used as a communication tool for clients and developers, which describes the entities involved in a given problem and the connections among them. It is worth to notice that humans can understand this model, but it is not comprehensive to computers. The latter transforms the entity – relationship model into structures that are implemented into a computer system known as Database Management System (DBMS). Once the database is running into the DBMS, programmers can build all the software applications to satisfy user’s needs.

Since databases design is a fundamental piece to develop reliable software systems, teachers and researchers continuously make many efforts to enhance students’ comprehension of it. Such attempts range from describing more and better classroom exercises to employ technological resources to explain some issues. In this way, we developed a Web classroom application that supports the learning of database design. Our proposal is a graphic editor focused on entity – relationship and relational diagrams. Besides the advantages of being a Web system, our work has the following benefits for the students: first, it considers concepts of traditional and extended entity – relationship model. Second, it is capable of detecting errors in the representations created by the student and to generate a complete report of mistakes as well as a list of suggestions to correct them. By so doing, the students not only can observe their faults but also have an idea of how to fix them. Third, it implements a transformation algorithm which takes the entity – relationship model and generates its corresponding relational representation. As far as we know, there are no editors with the cited characteristics.

Using a group of 30 students of the third semester of the degree in Computer Systems Engineering, we performed two types of evaluation over our system; the first one checked the tool itself by employing usability tests. The second one examined the system’s utility to the students’ learning. Regarding system’s usability we conclude that, compared with existing projects, our proposal improves the representations made by students since it is focused on database design, and it takes less than one hour to learn how to use it. To check the impact of the tool on the students’ learning, all of them solved a diagnostic test after the related topics were explained. The average mark was 7.5. Then, a list of 10 problems was assigned to them. We divided the group in two subgroups; the first one solved their problems in a conventional way and the second one used the tool. At the end, a new test was applied to both groups. The average grade obtained by the first subgroup was 8.0 and the average grade obtained by the second subgroup was 8.4. It is important to notice that besides the improvement in the average grade, the students of the second subgroup could explain and justify satisfactorily their designs which didn’t happen with the students of the first subgroup. This fact suggests that our system had a positive effect in the students’ learning of database design.

Keywords:

Learning, Web application, higher levels.