Although instruction on meiosis is repeated many times during the undergraduate curriculum, many students show poor comprehension even as upper-level biology majors. We propose that the difficulty lies in the complexity of understanding DNA, which we explain through a new model, the DNA triangle. The "DNA triangle" integrates three…

Investigated use of overhead transparencies containing a sequence of diagrams to represent a three-dimensional structure at different stages during a rotation. Significant learning occurred among 120 Bahraini boys (aged 15-16) when the transparencies contained multi-colored diagrams which were exposed simultaneously or individually in a cumulative…

Described is research conducted on cluster-assembled matter. The differing character of these arrangements of matter are discussed. Methods used to produce clusters are reviewed. (CW)

Examined are the illustrations and descriptions of the molecular structure of sulfur dioxide found in selected chemistry textbooks. Inconsistencies and incorrect information are indicated. It is suggested that molecules other than sulfur dioxide be used as examples of molecules for which resonance is important. (CW)

Describes a computer program that allows undergraduate students to undertake nomenclature tutorials in organic chemistry, where user response is evaluated based on a set of rules that determine appropriate feedback. Design of the software is described, including the use of computer graphics, and results of students' evaluations are briefly…

Determined the factor structure of tasks which require students to visualize how diagrams should be drawn to represent effects of rotating three-dimensional structures about the three Cartesian axes. Results obtained from 149 English and 231 Singapore students show that visualization about X-, Y-, and Z-axes are factorially distinct. (DH)

Discussed are some of the strategies required to try to detect and explain DNA markers that account for small amounts of behavioral variation. Situations in both animal and human behavior are described. The link between molecular biology and behavior is highlighted. (CW)

The pencil-and-paper assignment "Represent water in its three states using a model" was given to pupils (n=227) from eighth to twelfth grades. The findings show that the dominant model used was the space filling type; movement of particles was indicated by a minority of pupils; size of the model changed when drawn in different states.…

The purpose of this study was twofold: (1) to understand the conceptual frameworks that sixth-grade students use to explain the nature and structure of matter and molecules; and (2) to assess the effectiveness of two alternate instructional units in helping students change those conceptions. The study involved 15 sixth-grade classes taught by 12…

This paper describes the development of a sixth-grade "Matter and Molecules" unit using a new curriculum development model based on conceptual change research, the field testing of this unit in 15 classrooms and the field test results. The development process and the resulting unit are contrasted with the unit's predecessor, the "Models of Matter"…

An understanding of the concepts of atoms and molecules is fundamental to the learning of chemistry. Any misconceptions and alternative conceptions related to these concepts which students harbor will impede much further learning. This paper identifies misconceptions related to the fundamental characteristics of atoms and molecules which Grade 12…

Reports on a study into the relationship between a student's ability to solve problems in chemistry and his/her understanding of molecular concepts. Argues that teaching students to solve problems about chemistry is not equivalent to teaching about the nature of matter. (TW)

Two experiments were conducted to assess the performance of freshmen chemistry students with poor spatial visualization skills. In the first experiment, 31 chemistry students with academically deficient backgrounds completed a diagnostic test of their ability to visualize and interpret pictorial representations of simple molecular structures. At…

Reports on a study which examined the relationship between spatial ability and performance in organic chemistry. Results indicated that students with high spatial scores did significantly better on questions requiring problem solving skills, as well as on those requiring the mental manipulation of two-dimensional representations of a molecule. (TW)

Presented is a comprehensible structural representation of humic substances. A number of important roles of soil organic matter, including contribution to the cation-exchange capacity, binding of pesticides, and formation of complexes with micronutrient cations, are illustrated. (Author/CW)