Stoichiometry is an important topic in chemistry. It tells how many reactants are required to produce a certain amount of product in terms of mass, mole and volume. Learning stoichiometric calculation involves the understanding of certain concepts such as the mole, stoichiometric ratios and chemical equations. Some studies attributed the failure in learning stoichiometry to the unfamiliarity with the amount of substance in a mole and students’ weakness in the mathematical ability. Nevertheless how students connect the submicro level and the symbolic level in learning stoichiometry was not discussed widely. In this study, two examples of chemical reactions with different levels of difficulties were used to probe students’ conceptual understanding in stoichiometry at the submicro level. Their strategies used in stoichiometric calculations were examined by an interview study of five Secondary Five students. The connection between the submicro level and the symbolic level in learning stoichiometry would be also probed into. Results indicate that the failure of stoichiometry learning may due to the disconnection in different levels of representation and students’ generated strategy – ‘one portion reasoning’. An implication for teaching and learning is that teachers should use diagrams at the submicro level in the teaching of stoichiometry. Such diagrams should aim to help students building connections across the three levels of representation and enhancing students’ conceptual understanding in stoichiometry. / published_or_final_version / Education / Master / Master of Education

Cell division is a topic widely recognized by biology teachers for its importance in the curriculum. However, it is also regarded by teachers and students as a very difficult topic. Students at different school levels often hold many misconceptions in cell divisions. While diagrams have been so commonly employed in biology textbooks to enhance the textual representation of cell divisions, the researcher of this study questioned about the cognitive role of the diagrams in helping students construct new concepts of cell divisions, as well as students’ competence in learning from the diagrams. This exploratory study was conducted to investigate how secondary school students made use of textbook diagrams to gain new information about cell divisions, if and how the diagrams induced misconceptions in students, the problems students encountered when interpreting the diagrams and captions, and their perceptions of the usefulness of diagrams in learning cell divisions specifically and biology in general. Twenty-two secondary four students took part in this study. They were provided with a textbook illustration of mitotic and meiotic cell divisions, consisting of schematic diagrams and captions, for self-study. Data was collected from the students’ performance on a task sheet and their responses in individual interview. The task sheet assessed the new concepts (and/or misconceptions) constructed by the students through their (mis-)interpretation of the diagrams and captions in the illustration. The individual interview probed deeper into the students’ cognitive processing of the information in the illustration. Results showed that the students were able to employ different strategies to interpret the diagrams and captions to construct new knowledge to solve problems in the task sheet. However, they also showed weaknesses and problems in interpreting the diagrams. The problems included superficial processing of diagrams, lack of awareness and skills of interpreting diagram conventions, misinterpretation of temporal relationship among different diagrams or different diagram components. As a result, a number of misconceptions on cell divisions were detected among the students. These included misconceptions related to: (1) changes in chromosome number in cell divisions, (2) crossing over occurring at metaphase I of meiosis, and chromosome arrangement at metaphase I. The study also found that students generally perceived diagrams useful for learning cell divisions, but not for learning biology in general. They seemed to have underestimated the functions of textbook diagrams in representing biology concepts and undervalued the roles that diagrams may play in assessment of their understanding of biological concepts. The research findings contribute to the literature on misconceptions of cell divisions by uncovering students’ misinterpretation of specific kinds of diagrams as the origin of their learning difficulties. The findings also contribute to the growing literature on students’ visual perception and the power of diagrams for learning from science textbooks. Recommendations were made for textbook authors to improve design of diagrams illustrating scientific concepts, for teachers to equip students with visual literacy skills to learn from diagrams, and for teacher trainers to provide relevant training to pre-service and in-service teachers. Some suggestions for further research were also discussed. / published_or_final_version / Education / Master / Master of Education

This research utilized a structural analysis of final judgment and a process-tracing method to examine the effects of situational involvement and task complexity on information acquisition and the decision-making process. In addition, the predictive accuracy of the linear model in predicting drug choice across decision situations was assessed. A contingency model for the selection of decision strategies based on a cost/benefit principle was used as a framework in the study. A randomized mixed model factorial design was conducted in which a sample of forty-eight physicians, recruited from the University Medical Center at the University of Arizona, indicated their preferences and choices for hypothetical anti-infective drugs. Subjects were randomly assigned to experimental and control groups. Subjects in the experimental group were told via the written scenario to assume that his/her decision would be reviewed and evaluated by peers and (s)he would be asked to justify drug choice. No mention of peer review was made in the scenario used by the control group. Subjects in both groups were required to perform the two choice tasks and conjoint ranking task. The number of drug alternatives in a choice set was varied between three and six alternatives. The Mouselab program was used to monitor physicians' information acquisition behavior. The measures concerning the amount of information searched, order, duration, direction of search, and the chosen alternative were observed. The conjoint LINMAP program was used to estimate drug attribute importance weights. Results of the study provide support that the information acquisition and decision-making process is contingent on the characteristics of decision tasks. A significant number of subjects shifted from using compensatory to noncompensatory decision-making processes when task complexity increased. The study did not find support for the effects of situational involvement on the decision-making process. However, subjects in the two groups were found to differ in choice outcomes and the attention given to specific drug attribute information. Finally, the study found support for the robustness of the linear models in predicting drug choice across contexts.

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The problem which prompted this study was that of determining the causes for the drop-out of students in Spanish from first to second year at Thomas Carr Howe High School, Indianapolis, Indiana. For comparative purposes it seemed profitable to include also in the study those students who were continuing in order to ascertain any existing differences in composition.Behind this basic problem lay the fact, supported by figures compiled in the language department at Howe High School over a period of years, that approximately half the students which initiated foreign language study did not continue to a second year of that study. This evidently was not a local problem for in New England, where schools have long emphasized foreign language study, second-year enrollments have not far exceeded half the number of first-year enrollments. Although a consensus of opinion of teachers of modern foreign languages would reveal that real satisfaction of working with a language does not come to the student until the third and fourth years, and that the first two years are directed largely toward assimilating material which assists the student toward that goal, studies have shown that only about 12 per cent continue to their third year, and that approximately 60 per cent discontinue their study at the end of one year.1 Naturally these facts pose a problem for which many educators would like a solution.The information which results from this study should have value for all those who have contact with the teaching of languages at Howe High School but it is hoped that the information might also provide the impetus for studies of a similar nature at other schools and finally result in greater numbers of students continuing their modern language studies to the point that they might more completely enjoy the returns of their earlier labors.

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