Sanders, K., Boustedt, J., Eckerdal, A., McCartney, R., Mostr?m, J., Thomas, L., and Zander, C. 2008. Student understanding of object-oriented programming as expressed in concept maps. In Proceedings of the 39th SIGCSE Technical Symposium on Computer Science Education (Portland, OR, USA, March 12 - 15, 2008). SIGCSE '08. ACM, New York, NY, 332-336.In this paper, we present the results of an experiment in which we sought to elicit students' understanding of object-oriented (OO) concepts using concept maps. Our analysis confirmed earlier research indicating that students do not have a firm grasp on the distinction between 'class' and 'instance.' Unlike earlier research, we found that our students generally connect classes with both data and behavior. Students rarely included any mention of the hardware/software context of programs, their users, or their real-world domains. Students do mention inheritance, but not encapsulation or abstraction. And the picture they draw of OO is a static one: we found nothing that could be construed as referring to interaction among objects in a program. We then discuss the implications for teaching introductory OO programming.Non peer reviewe

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, European Journal of Engineering Education, 1469-5898, Volume 34, Issue 4, 2009, Pages 383 ? 391.'Threshold concepts' are concepts that, among other things, transform the way a student looks at a discipline. Although the term 'threshold' might suggest that the transformation occurs at a specific point in time, an 'aha' moment, it seems more common (at least in computing) that a longer time period is required. This time period is referred to as the 'liminal space'. In this paper, we summarise our findings concerning how computing students experience the liminal space and discuss how this might affect teaching. Most of our findings so far relate to software engineering. As it is likely that similar liminal spaces occur in other engineering disciplines, these findings have relevance across engineering education.Peer reviewe

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The software industry needs well-trained software designers and one important aspect of software design is the ability to model software designs visually and understand what visual models represent. However, previous research indicates that software design is a difficult task to many students. This article reports empirical findings from a phenomenographic investigation on how students understand class diagrams, Unified Modeling Language (UML) symbols, and relations to object-oriented (OO) concepts. The informants were 20 Computer Science students from four different universities in Sweden. The results show qualitatively different ways to understand and describe UML class diagrams and the ''diamond symbols'' representing aggregation and composition. The purpose of class diagrams was understood in a varied way, from describing it as a documentation to a more advanced view related to communication. The descriptions of class diagrams varied from seeing them as a specification of classes to a more advanced view, where they were described to show hierarchic structures of classes and relations. The diamond symbols were seen as ''relations'' and a more advanced way was seeing the white and the black diamonds as different symbols for aggregation and composition. As a consequence of the results, it is recommended that UML should be adopted in courses. It is briefly indicated how the phenomenographic results in combination with variation theory can be used by teachers to enhance students' possibilities to reach advanced understanding of phenomena related to UML class diagrams. Moreover, it is recommended that teachers should put more effort in assessing skills in proper usage of the basic symbols and models and students should be provided with opportunities to practise collaborative design, e.g. using whiteboards.

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