Abstracts - Earli

understanding of the concepts of limit and integral, and then to reflect in writing on the meaning ofthese concepts. A sub-sample of four students was selected for subsequent interviews exploring ingreater detail individual students’ conceptual understandings. Intentional analysis of the students’written and oral accounts revealed that the students were communicating their understanding oflimit and integral within an algorithmic context, in which the very ‘operations’ of these conceptswere seen as crucial features. The students also displayed great confidence in their ability to dealwith these concepts. It is argued that developing understanding within an algorithmic context canbe seen as a stepping stone towards developing a more complete conceptual understanding ofcalculus. These results are discussed in relation to on-going research on threshold concepts inhigher education, and it is suggested that while the notion of threshold concept points up potentialdifficulties involved in coming to understand particular parts of a subject area, the notion of‘threshold function’ offers an opportunity to explore difficulties and potentialities of students’learning from the contextually sensitive perspectives of the students themselves.N 1731 August 2007 16:00 - 17:20Room: 0.79 JánossyPaper SessionComprehension of text and graphicsChair:Zoltán Tóth, KLTE, HungaryAn exploration of students’ semantic understanding of ‘kind-of/part-of’ discoursesWen-Gin Yang, Graduate Institute of Science education, NTNU, TaiwanShih-Wen Chen, Graduate Institute of Science Education, NTNU, TaiwanThis study aimed at exploring different levels students’ understandings of the ‘kind-of/part-of’relations of science objects described in science text. To describe such relations variety ofdiscourses, ranging from explicit to implicit, could be deployed. In doing that ambiguities wouldbe encountered when readers trying to make sense of the relations among objects. A text of bloodwas excerpted from current junior high science textbook as the target text. The text comprises offive sentences, 157 Mandarin characters, and 13 events in the sense of transitivity analysis; aninstrument of 25 items was constructed by rewording or transforming the kind-of/part-ofdiscourses into kind-of or part-of ones. Totally 329 subjects, 142 7th graders, 149 9th graders, and38 pre-service and in-service science teachers, participated in this study. They were asked to readthe blood and then answer the questions with permission to refer to the blood text. The reliability(λ5) is 0.76. Major quantitative findings include: (1) readers interpret the semanticmeaning differently even for cases of explicit kind-of/part-of discourses; (2) in cases of implicitdiscourses the variation of interpretation increased; (3) significance differences were observedacross different levels of readers; (4) readers inclined to perceive the part-of relations amongscience objects as ‘ingredient/compound’ or ‘compositional’ ones. The reasons of readers’interpretation were also analyzed qualitatively. Finally, the implications of the findings for sciencetext writing and science teaching were discussed.– 757 –