In this paper we report on the process of argument construction in whole class discussions and how this was used by participants as a tool for joint meaning-making. The study draws on Vygotsky's view of learning as the active construction of knowledge and on theories of argumentation. Most previous research in South African science classrooms has…

Mixed-format assessments are increasingly being used in large scale standardized assessments to measure a continuum of skills ranging from basic recall to higher order thinking skills. These assessments are usually comprised of a combination of (a) multiple-choice items which can be efficiently scored, have stable psychometric properties, and…

Student retention has been a challenge for higher education institutions, an urgent issue that must be reassessed and improved at these institutions. It is essential for many Hispanic-serving institutions (HSIs) that have a high percentage of Hispanic populations to find ways where they will support and retain a growing number of minority…

Chemistry graduate education is under considerable pressure. Pharmaceutical companies, long a major employer of synthetic organic chemists, are drastically paring back their research divisions to reduce costs. Chemical companies are opening new research and development facilities in Asia rather than in the United States to take advantage of…

Reform movements in science education have repeatedly called for more dialogic and student-centered discussions during science lessons. The approach secondary science teachers take towards talk during whole-class discussions continues to be predominantly teacher-centered even when curriculum materials are designed to support a shift in discourse.…

In this study, we test an information-processing model (IPM) of problem solving in science education, namely the working memory overload model, by applying catastrophe theory. Changes in students' achievement were modeled as discontinuities within a cusp catastrophe model, where working memory capacity was implemented as asymmetry and the degree…

This paper introduces a research project in which five chemistry teachers, working in cooperation with university researchers, implemented a new teaching approach using context-based modules specially designed to stimulate the intrinsic motivation of students. The intention was to induce change in chemistry teachers' teaching approach from more…

Using the responses to open questions, this qualitative study examines the personal metaphors expressed by prospective secondary education teachers, 46 science graduates and 41 economics graduates. The metaphors are classified into the four categories of Leavy, McSorley, and Bote: the behaviourist/transmissive, the cognitivist/constructivist, the…

Despite numerous calls for reform, the early chemistry experience for most college students has remained unchanged for decades. In 2004 the National Science Foundation (NSF) issued a call for proposals to create new models of chemical education that would infuse authentic research into the early stages of a student's college experience. Under this…

The importance of research on misconceptions about chemical equilibrium is well recognized by educators, but in the past, researchers' interest has centered on student misconceptions and has neglected teacher misconceptions. Focusing on the effects of adding more reactants or products on chemical equilibrium, this article discusses the various…

We performed theoretical studies on the systems NH[subscript 3] times HF times mH[subscript 2]O, NH[subscript 3] times HCl times mH[subscript 2]O, with m = 0, 1, 2, and 6. The molecules with m = 0 form hydrogen-bonded adducts with little tendency to form an ion-pair structure. The molecule NH[subscript 3] times HCl times H[subscript 2]O cannot be…

In this study, performance of a hydrogen-peroxide-driven car has been simulated using basic conservation laws and a few numbers of auxiliary equations. A numerical method was implemented to solve sets of highly non-linear ordinary differential equations. Transient pressure and the corresponding traveled distance for three different car weights are…

Metolachlor is one of the most widely used agents registered for the protection of many cultivated plants against weeds. Because of axial and central chirality, this molecule forms four stereoisomers, the investigation of which by [superscript 1]H NMR and chromatography is described. It is shown that the isomers do not interconvert at room…

Terms to be familiar with before you start to solve the test: polymerase chain reaction, DNA amplification, electrophoresis, breast cancer, "HER2" gene, genomic DNA, "in vitro" DNA synthesis, template, primer, Taq polymerase, 5[prime][right arrow]3[prime] elongation activity, 5[prime][right arrow]3[prime] exonuclease activity, deoxyribonucleoside…

Derivation of the second- and higher-order virial coefficients for models of the gaseous state is demonstrated by employing a direct differential method and subsequent term-by-term comparison to power series expansions. This communication demonstrates the application of this technique to van der Waals representations of virial coefficients.…