Upper Secondary Teachers' Knowledge for Teaching Chemical Bonding Models

Researchers have shown a growing interest in science teachers’ professional knowledge in recent decades. The article focuses on how chemistry teachers impart chemical bonding, one of the most important topics covered in upper secondary school chemistry courses. Chemical bonding is primarily taught using models, which are key for understanding science. However, many studies have determined that the use of models in science education can contribute to students’ difficulties understanding the topic, and that students generally find chemical bonding a challenging topic. The aim of this study is to investigate teachers’ knowledge of teaching chemical bonding. The study focuses on three essential components of pedagogical content knowledge (PCK): (1) the students’ understanding, (2) representations, and (3) instructional strategies. We analyzed lesson plans about chemical bonding generated by 10 chemistry teachers with whom we also conducted semi-structured interviews about their teaching. Our results revealed that the teachers were generally unaware of how the representations of models they used affected student comprehension. The teachers had trouble specifying students’ difficulties in understanding. Moreover, most of the instructional strategies described were generic and insufficient for promoting student understanding. Additionally, the teachers’ rationale for choosing a specific representation or activity was seldom directed at addressing students’ understanding. Our results indicate that both PCK components require improvement, and suggest that the two components should be connected. Implications for the professional development of pre-service and in-service teachers are discussed.     

Effectiveness of multimedia‐based instruction that emphasizes molecular representations on students' understanding of chemical change

The present study makes use of the capabilities of computerized environments to enable simultaneous display of molecular representations that correspond to observations at the macroscopic level. This study questions the immediate and long‐term effects of using a multimedia instructional unit that integrates the macroscopic, symbolic, and molecular representations of chemical phenomena. Forty‐nine eighth graders received either multimedia‐based instruction that emphasized molecular representations (n = 16), or regular instruction (n = 33). Students who received multimedia‐based instruction that emphasized the molecular state of chemicals outperformed students from the regular instruction group in terms of the resulting test scores and the ease with which they could represent matter at the molecular level. However, results relating to the long‐term effects suggest that the effectiveness of a multimedia‐based environment can be improved if instruction includes additional prompting that requires students to attend to the correspondence between different representations of the same phenomena. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 317–337, 2004     

Teaching the Nature of Inquiry: Further Developments in a High School Genetics Curriculum

In order for students to truly understand science, we feel that they must be familiar with select subject matter and also understand how that subject matter knowledge was generated and justified through the process of inquiry. Here we describe a high school biology curriculum designed to give students opportunities to learn about genetic inquiry in part by providing them with authentic experiences doing inquiry in the discipline. Since a primary goal of practicing scientists is to construct explanatory models to account for natural phenomena, involving students in the construction of their own explanatory models provides a major emphasis in the classroom. The students work in groups structured like scientific communities to build, revise, and defend explanatory models for inheritance phenomena. The overall instructional goals include helping students understand the iterative nature of scientific inquiry, the tentativeness of specific knowledge claims (and why they should be considered tentative), and the degree to which scientists rely on empirical data as well as broader conceptual and metaphysical commitments to assess models and to direct future inquiries.     

Lecturers’ vs. students’ perceptions of the accessibility of instructional materials

This goal of this study was to examine the differences between lecturers and students’ perceptions of the accessibility of instructional materials. The perceptions of 12 mature computing distance education students and 12 computing lecturers were examined using the knowledge elicitation techniques of card sorting and laddering. The study showed that lecturers had pedagogical views while students tended to concentrate on surface attributes such as appearance. Students perceived instructional materials containing visual representations as most accessible. This has two implications for the professional development of computing lecturers designing instructional materials. First, lecturers need to appreciate the differences between expert and novice views of accessibility and how students will engage with the materials. Second, lecturers need to understand that learners perceive instructional materials containing visual representations as more accessible compared to ‘text only’ versions. Hence greater use of these may enable students to engage more readily in learning. Given that print is the ubiquitous teaching medium this is likely to have implications for students and lecturers in other disciplines.     

On-Site Pedagogical Content Knowledge Development

Experiences and reflection have long been regarded as a foundation for pedagogical content knowledge (PCK) development. However, little is known about how experienced teachers develop their PCK via reflection-in-action during their moment-to-moment classroom instruction. Drawing upon data sources including classroom observations, semi-structured interviews and stimulated recall interviews based on lesson videos, this study examined instances when four experienced teachers were found to invent new instructional strategies/representations on the spot during the lesson (referred to as on-site PCK development) in their first attempts at teaching a new topic. The study documented the moment-to-moment experiences of the teachers, including their reconstructed thought processes associated with these instances of on-site PCK development. An explanatory model of a three-step process comprising a stimulus, an integration process and a response was advanced to account for the on-site PCK development observed among the teachers. Three categories of stimulus that triggered on-site PCK development were identified. Factors influencing the integration process and, hence, the resulting response, included teachers’ subject matter knowledge of the new topic, their general pedagogical knowledge and their knowledge of student learning difficulties/prior knowledge related to the new topic. Implications for teacher professional development in terms of how to enhance teachers’ on-site PCK development are discussed.     

Teachers and Students’ Conceptions of Computer-Based Models in the Context of High School Chemistry: Elicitations at the Pre-intervention Stage

This study examined teachers’ and students’ initial conceptions of computer-based models—Flash and NetLogo models—and documented how teachers and students reconciled notions of multiple representations featuring macroscopic, submicroscopic and symbolic representations prior to actual intervention in eight high school chemistry classrooms. Individual in-depth interviews were conducted with 32 students and 6 teachers. Findings revealed an interplay of complex factors that functioned as opportunities and obstacles in the implementation of technologies in science classrooms. Students revealed preferences for the Flash models as opposed to the open-ended NetLogo models. Altogether, due to lack of content and modeling background knowledge, students experienced difficulties articulating coherent and blended understandings of multiple representations. Concurrently, while the aesthetic and interactive features of the models were of great value, they did not sustain students’ initial curiosity and opportunities to improve understandings about chemistry phenomena. Most teachers recognized direct alignment of the Flash model with their existing curriculum; however, the benefits were relegated to existing procedural and passive classroom practices. The findings have implications for pedagogical approaches that address the implementation of computer-based models, function of models, models as multiple representations and the role of background knowledge and cognitive load, and the role of teacher vision and classroom practices.     

The effects of prior knowledge and instruction on understanding image formation

This paper reports on a study that was designed to investigate the knowledge about image formation exhibited by students following instruction in geometrical optics in an activity-based college physics course for prospective elementary teachers. Students were interviewed individually, using several tasks involving simple apparatus (plane and curved mirrors, lenses, and prisms). The diagrams drawn by the students and the verbal comments they made provide evidence that their knowledge can be described as an intermediate state, a hybridization of preinstruction knowledge (which is dominated by a holistic conceptualization) and formal physics knowledge. We infer from our data the core concepts and main ideas of the postinstruction students' hybrid knowledge. Finally, by comparing preinstruction and formal physics conceptualizations of image formation we argue that a strong type of knowledge restructuring (in the sense of Carey, S., 1986: American Psychologist, 41, 1123-1130; Vosianou, S., & Brewer, W.F., 1987: Review of Educational Research, 57, 51-67) is required for students to acquire the latter.     

Making connections among multiple visual representations: how do sense-making skills and perceptual fluency relate to learning of chemistry knowledge?

To learn content knowledge in science, technology, engineering, and math domains, students need to make connections among visual representations. This article considers two kinds of connection-making skills: (1) sense-making skills that allow students to verbally explain mappings among representations and (2) perceptual fluency in connection making that allows students to fast and effortlessly use perceptual features to make connections among representations. These different connection-making skills are acquired via different types of learning processes. Therefore, they require different types of instructional support: sense-making activities and fluency-building activities. Because separate lines of research have focused either on sense-making skills or on perceptual fluency, we know little about how these connection-making skills interact when students learn domain knowledge. This article describes two experiments that address this question in the context of undergraduate chemistry learning. In Experiment 1, 95 students were randomly assigned to four conditions that varied whether or not students received sense-making activities and fluency-building activities. In Experiment 2, 101 students were randomly assigned to five conditions that varied whether or not and in which sequence students received sense-making and fluency-building activities. Results show advantages for sense-making and fluency-building activities compared to the control condition only for students with high prior chemistry knowledge. These findings provide new insights into potential boundary conditions for the effectiveness of different types of instructional activities that support students in making connections among multiple visual representations.     

Visual Representations of DNA Replication: Middle Grades Students’ Perceptions and Interpretations

Visual representations play a critical role in the communication of science concepts for scientists and students alike. However, recent research suggests that novice students experience difficulty extracting relevant information from representations. This study examined students’ interpretations of visual representations of DNA replication. Each of the four steps of DNA replication included in the instructional presentation was represented as a text slide, a simple 2D graphic, and a rich 3D graphic. Participants were middle grade girls (n = 21) attending a summer math and science program. Students’ eye movements were measured as they viewed the representations. Participants were interviewed following instruction to assess their perceived salient features. Eye tracking fixation counts indicated that the same features (look zones) in the corresponding 2D and 3D graphics had different salience. The interviews revealed that students used different characteristics such as color, shape, and complexity to make sense of the graphics. The results of this study have implications for the design of instructional representations. Since many students have difficulty distinguishing between relevant and irrelevant information, cueing and directing student attention through the instructional representation could allow cognitive resources to be directed to the most relevant material.     

Research in Science Education at the University of Glasgow

The purpose of this study was to examine how prior knowledge of cellular transport influenced how high school students in the USA viewed and interpreted graphic representations of this topic. The participants were Advanced Placement Biology students (n = 65); each participant had previously taken a biology course in high school. After assessing prior knowledge using the Diffusion and Osmosis Diagnostic Test, two graphical representations of cellular transport processes were selected for analysis. Three different methods of data collection—eye tracking, interviews, and questionnaires—were used to investigate differences in perceived salient features of the graphics, interpretations of the graphics, and processing difficulty experienced while attending to and interpreting the graphics. The results from the eye tracking data, interviews, and instructional representation questionnaires were triangulated and revealed differences in how high and low prior knowledge students attended to and interpreted particle differences, concentration gradient, the role of adenosine triphosphate , endocytosis and exocytosis, and text labels and captions. Without adequate domain knowledge, low prior knowledge students focused on the surface features of the graphics (ex. differences in particle colour) to build an understanding of the concepts represented. On the other hand, with more abundant and better‐organised domain knowledge, high prior knowledge students were more likely to attend to the thematically relevant content in the graphics, which enhanced their understanding. The findings of this study offer a more complete understanding of how differentially prepared learners view and interpret graphics and have the potential to inform instructional design.     

An exploration of the interactions among the components of an experienced elementary science teacher’s pedagogical content knowledge

This study had two purposes: to explore the components of the pedagogical content knowledge (PCK) of an experienced elementary science teacher and to reveal the presumed interactions among these components. A naturalistic inquiry was conducted as a single case study in which in-depth qualitative data were gathered through semi-structured interview questions. After the theory-based and data-driven analysis of the qualitative data, the verbal communication was quantitated into numerical data for the enumerative analysis. The results revealed that the teacher’s knowledge of students’ understanding and difficulties, knowledge of the elementary science curriculum and knowledge of instructional strategies and representations were found to be mostly intersected PCK components, whereas orientations towards teaching science and knowledge of assessment in science had limited connections to the other components. Further discussions and context-based suggestions are given regarding professional development programmes.     

Toward a Framework for Using Student Mathematical Representations as Formative Assessments

This article explores how students' mathematical representations can be used as formative assessments. We introduce a framework for teaching and learning that integrates representations as instructional and assessment tools, and illustrate these uses of student representations with reference to a study conducted with 250 5th-grade students. This study focused on students' ability to recognize and use a variety of representations of the fraction concept. Finally, we discuss the implications of the framework for teacher knowledge and classroom practice.     

Prospective teachers’ learning to provide instructional explanations: how does it look and what might it take?

Several studies have documented prospective teachers’ (PSTs) difficulties in offering instructional explanations. However, less is known about PSTs’ learning to provide explanations. To address this gap, we trace changes in the explanations offered by a purposeful sample of PSTs before and after a mathematics content/methods course sequence. Consistent with prior research, our study reveals the limitations in PSTs’ explanations at their entrance to the course sequence. It also documents PSTs’ progress in providing explanations, thus providing existence proof that this practice is learnable. Using evidence from multiple sources, we also propose a component entailed in this learning—learning how to unpack one’s thinking through the use of representations as explanatory tools—and four factors associated with it, including PSTs’ subject-matter knowledge, active and deliberate reflection on practice, productive images for engaging in this work, and productive dispositions about engaging in this practice. We discuss the implications of our findings for teacher education and offer directions for future research.     

Learning by self-explaining causal diagrams in high-school biology

Understanding scientific phenomena requires comprehension and application of the underlying causal relationships that describe those phenomena (Carey 2002). The current study examined the roles of self-explanation and meta-level feedback for understanding causal relationships described in a causal diagram. In this study, 63 Korean high-school students were randomly assigned to one of three conditions: instructional explanation, self-explanation, and meta-level feedback. Results showed that self-explaining a causal diagram was as effective as studying instructional explanations. Furthermore, the effectiveness of self-explaining a causal diagram was enhanced by meta-level feedback that prompted students to reflect on their own explanations by comparing them with instructional explanations. We identified three main difficulties that high-school students experienced when explaining a causal diagram to themselves: one-sided explanation, erroneous explanation, and the lack of inference. Implications of the study were discussed in regard to the improvement of self-explanation and the design of causal diagrams in science education.     

Selective use of animation and feedback in computer-based instruction

The effects of two computer-based instructional strategies—visual display and feedback type—were investigated in the acquisition of electronic troubleshooting skills. Animation was used to simulate the functional behaviors of electronic circuits and to demonstrate the troubleshooting procedures. The first hypothesis tested was that animated visual displays would be more effective than static visual displays if animation was selectively used to support the specific learning requirements of a given task. Results supported this hypothesis by showing that college students in the animated visual display condition needed significantly fewer trials than those in the static visual display condition. The second hypothesis was that the effectiveness of intentionally mediated feedback (knowledge of results or explanatory information) would be minimal if natural feedback—the system's automatic functional reaction to external inputs—was available and the subject had the basic knowledge needed to understand the system functions. The results supported this hypothesis. Overall, this study implies that instructional strategies, including visual displays and feedback, should be applied selectively based on the specific learning requirements of a given task. he works at ARI as a research fellow of the Universities of the Washington Metropolitan area. The opinions expressed herein are those of the authors and do not express or imply the views of the U. S. Army Research Institute or the Department of Defense. The authors would like to thank Eric C. Neiderman and Reginald Hopkins for their assistance with this study.     

ANALYSIS OF STUDENT UNDERSTANDING OF SCIENCE CONCEPTS INCLUDING MATHEMATICAL REPRESENTATIONS: pH VALUES AND THE RELATIVE DIFFERENCES OF pH VALUES

In general, mathematical representations such as formulae, numbers, and graphs are the inseparable components in science used to better describe or explain scientific phenomena or knowledge. Regardless of their necessity and benefit, science seems to be difficult for some students, as a result of the mathematical representations and problem solving used in scientific inquiry. In this regard, several studies have attributed students’ decreasing interest in science to the presence of these mathematical representations. In order to better understand student learning difficulties caused by mathematical components, the current study investigates student understanding of a familiar science concept and its mathematical component (pH value and logarithms). Student responses to a questionnaire and a follow-up interview were examined in detail. “Measure” and “concentration” were key criteria for students’ understanding of pH values. In addition, only a few students understood logarithms on a meaningful level. According to students’ understanding of scientific phenomena and mathematical structures, five different student models and the critical features of each type were identified. Further analysis revealed the existence of three domains that characterize these five types: object, operation, and function. By suggesting the importance of understanding scientific phenomena as a “function,” the current study reveals what needs to be taught and emphasized in order to help students obtain a level of scientific meaning that is appropriate for their grade.     

Constructing explanatory models from text-based information: Why instructional tools help

Scientists frequently construct explanatory models based on information they read about scientific phenomena. Modeling is a complex task involving reasoning about what information from multiple texts, including verbal and visual representations, is task-relevant and how it relates to the model. In this study, ninth graders were randomly assigned to a text-based modeling task with or without an instructional tool designed to support selection and elaborative processing of relevant information. Participants completed prompted self-explanation protocols during the modeling task and a learning task afterward. Participants with the instructional tool demonstrated better model construction and learning. Self-explanation analyses indicated more elaborative processing of relevant information for those with the tool. Elaboration of relevant information significantly mediated the instructional tool effect, indicating that it is not the tool, but the forms of processing that it encouraged, that underlies better model construction and learning. Implications for science literacy instruction are discussed.