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

A Dissertation submitted to the Faculty of Education, University of the Witwatersrand, Johannesburg, for the degree of Master of Education. / Three-dimensional visualisation is an important skill in chemistry but one in which many students experience difficulty. The main aims of this research were to identify the nature, extent and particularly the reasons for university students' difficulties in three-dimensional thinking and to devise teaching strategies for overcoming them. The research was restricted to the simpler aspects of three-dimensional thinking; it dealt only with rotation and reflection of simple molecules. The component steps required for the solution of three-dimensional problems were identified, and students' competence in these steps was tested. Pretest results showed that the students initially had poor visuaIisation skills. The main reasons for their difficulties were identified to be: (a) inability to visualise the three-dimensional structures of molecules, using the depth cues; (b) lack of precise understanding of the meaning of the phrases used in the questions (such as rotation about the X-axis; reflection in the XY plane); (c) inability to visualise the orientation of the axes and planes and of the positions of the atoms after an operation. A ninety minute remedial instruction programme on those aspects which caused difficulty was found to be enough, as shown by an analysis of covariance, to improve the students' visualisation skills very significantly (p < 0,01). / AC 2018

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Thesis (Ph. D.)--University of Wisconsin--Madison, 1968. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

This study investigated possible alternative Chemistry teaching methods to improve the learning and thus the pass rate of the learners of access programmes at the Port Elizabeth Technikon. The study traced Chemistry learning from the Pre-Technician course to the present Science Foundation Certificate. Since the latter programme is a new course with new criteria, only implemented since the beginning of 2003, it provided a suitable platform for the evaluation and updating, if necessary, of new teaching methods. The study was limited to the subject of Chemistry. The participating learners in this qualitative research were fully informed of the objectives of this research and, for ethical reasons, their identities were protected. The methodology chosen was action research, which will include discussions regarding the choice, necessity and value of the research method. The following tools were used to collect data to determine approaches to learning and how the examination results were influenced: Questionnaires; Journal entries of students; Interviews; Data of examination results.

This study compares methods to evaluate the outcomes of laboratory instruction in high school chemistry and reports the instruments developed for that purpose. The objectives evaluated were: the ability of students in basic laboratory skills, ability of pupils in the selection of materials, apparatus and methods; and facts that are outcomes of laboratory instruction. These three objectives were selected from some fourteen general objectives gleaned from the literature pertaining to laboratory chemistry. They were chosen as representing outcomes due solely to laboratory instruction as compared with others that may have been achieved at least in part, by the routine lessons. The experimental method was to evaluate 72 high school students of chemistry by means of: 1. a practical test of laboratory work designed to conform with the objectives chosen referred to as the criterion test. 2. a group pencil and paper test somewhat parallel to the criterion test. 3. the laboratory notebooks of the students. 4. the teacher's estimates of student progress toward the objectives. Three classes of chemistry were evaluated in the Spring of 1952. The teacher's estimates were prepared in February from observation of the students at work in the laboratory. The laboratory reports had been marked weekly for six months prior to the experiment and the total score on fifteen reports was taken as a measure of the notebooks to assess laboratory knowledge. In March the criterion test was administered in two sections. Section I tested chiefly manipulations and was an individual test. Section II consisted of a series of small tests based on the course of study. About one week later the group pencil and paper test was administered to the three classes in successive class periods. The test consisted of two parts: 1. multiple-choice items, and 2. items matching diagrams with statements. The following statistical measures were reported for all tests: mean, standard deviation, reliability. For the criterion and pencil paper test the following were also reported: internal consistency of test items with their difficulties. The validities of the items of the pencil and paper test were also reported. The correlations between the different tests were calculated as a means of appraising the predictive value of each. The simple regression and multiple regression equations and beta coefficients for predicting the criterion from the pencil and paper test were compared. T-scores were tabled for the pencil and paper test as well as derived scores on the basis of a mean of 63 and a standard deviation of 13, designed so as to set 50 as the critical score to cut off 15 percent of the testees. To compare the ability of the test to predict the upper quarter on the criterion with the lower quarter, a chi-square test of significance was applied. The following conclusions appear to be defensible: 1. The group pencil and paper test, in predicting the criterion, was significantly superior to other methods, 2. The laboratory notebooks failed significantly to predict the outcomes being tested, 3. The teacher's estimates did not materially assist the pencil and paper test to predict the outcomes being tested, 4. The two tests possess a range of difficulty conforming to the requirements of a good test, 5. The test items having indices of validity of less than .23 contribute little to the predictive value of the pencil and paper test. 6. The pencil and paper test predicts the criterion equally well at either the upper or lower levels. / Education, Faculty of / Graduate

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See fulltext. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2011.

There is no abstract available for this thesis.