Stoichiometry calculation competence tends to be particularly poor in the developing world, even among teachers. Various methods, including the unit factor method, have the potential to be effective in developing such competence. To evaluate the likelihood of such a generic proportion method, which downplays traditional formula usage, succeeding in a particular context, it is necessary first to understand teachers’ existing competence with proportion and the extent to which their calculation success relies on the explicit provision of and substitution into formulae in their written solutions. This quantitative survey study of 171 South African Physical Sciences teachers’ use of formulae and proportion found that most teachers failed to recognise the need to use proportion for some of the four reaction-based stoichiometry calculation questions used. Provision of and substitution into a formula in the written solution was found to be valuable in helping participants who underutilised proportion to obtain process marks, but to be largely irrelevant to obtaining the correct answer. The findings suggest that professional development interventions in similar contexts should focus on proportion within stoichiometry, particularly on recognition of its relevance to reaction-based questions. While a generic proportion method is well suited to this purpose, questions are raised concerning the likelihood that teachers would accept such a method in a context where process marks favour traditional formats of formula provision and substitution and where process mark attainment is highly valued. The findings also point to the need for teacher education to address competencies other than proportion.

There is a growing literature on the educational benefits of using podcasting of lectures in higher education, but to date little research that interrogates closely its impact on student learning. The present study investigated how students used lecture podcasts when produced in two engineering courses at a South African university. The findings confirm much of the growing consensus in the literature. Firstly, a majority of students in the courses elected to use the podcasts. Secondly, the study notes that lecture attendance, in contexts where lectures are seen as beneficial, is not adversely affected. Thirdly, few students use podcasts in the mobile mode but most rather use them as an additional resource in their private study spaces. There is intense use in the build up to tests and examinations, and there is a particular benefit for students who are not first language speakers of the medium of instruction. This study also points to the existence of both deep and surface approaches to engaging with podcasts, with substantial evidence of many students using podcasts as a means towards better understanding.

Teachers’ conceptual subject matter knowledge of stoichiometry is a global concern. Such knowledge is contextually dependent, as is the feasibility of attaining particular outcomes during in-service teacher education workshops. In an attempt to understand what is feasible in various contexts, I explore the relationships between South African physical sciences teachers’ environments, education, and teaching experience and their possession of, and ease with which they learn, various types of stoichiometry knowledge. This is done through the analysis of the pre- and posttest and biographical survey data obtained from 184 teachers who attended a two-day stoichiometry workshop. The findings suggest that teachers teaching in contexts of poverty, particularly when lacking a B.Sc. degree, show a particularly high preference for algorithmic over conceptual knowledge. The success with which the teachers in the sample learned facts about relationships between concepts during the two-day workshop suggests that such an approach could provide an entry point into currently less feasible conceptual learning. No correlation was found between extent of tertiary chemistry study and stoichiometry subject matter knowledge, even for teachers with a B.Sc. degree. Statistically significantly higher levels of stoichiometry knowledge were found for the following teacher groupings compared to their counterparts: teaching in a school serving a socioeconomically more advantaged community; having over three years’ teaching experience; possessing a B.Sc. degree. The suggestions derived for in-service teacher education targets are likely to have relevance in developing countries and in developed countries where considerable socioeconomic differences exist.

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