A comparison of applied and theoretical knowledge of concepts based on the particulate nature of matter

This study compares 183 high school chemistry students' applied and theoretical knowledge of selected concepts based on the particulate theory. The concepts are dissolution, diffusion, effusion, and states of matter. A two-form instrument called the Physical Changes Concepts Test (PCCT) was developed for this study. The application form measures students' knowlege using everyday language. The theoretical form measures students' knowledge using scientific language. Students' formal reasoning ability was measured using the Test Of Logical Thinking (TOLT). The overall results of the two forms of the PCCT indicate that more than 40% of the students displayed alternative conceptions (ACs) of the concepts covered in the PCCT. The study found that students' formal reasoning ability and their preexisting knowledge are associated with their conceptions and use of the particulate theory. The analysis of the nature of students' ACs and their use of the particulate theory revealed a significant difference between students' applied and theoretical knowledge.     

A cross-age study of the understanding of five chemistry concepts

A sample of 100 students from junior high school physical science, high school chemistry, and introductory college chemistry were examined for understanding of five chemistry concepts. The concepts addressed were chemical change, dissolution of a solid in water, conservation of atoms, periodicity, and phase change. The amount of experience with the concepts (grade level) and reasoning ability (developmental level) were examined as possible sources of variation in student understanding. Differences in understanding with respect to grade level were found to be significant for the concepts of chemical change, dissolution of a solid, conservation of atoms, and periodicity. However, few of the students in the college chemistry sample exhibited sound understanding of chemical change, periodicity, or phase change. The use of particulate terms (atoms, ions, molecules) increased across the grade levels. Reasoning ability proved to be a significant factor for student understanding of conservation of atoms and periodicity. An examination of the number and types of misconceptions across the grade levels revealed several interesting patterns and suggested sources for the students' alternative conceptions.     

An Investigation into the Relationship between Students’ Conceptions of the Particulate Nature of Matter and their Understanding of Chemical Bonding

A thorough understanding of chemical bonding requires familiarity with the particulate nature of matter. In this study, a two‐tier multiple‐choice diagnostic instrument consisting of ten items (five items involving each of the two concepts) was developed to assess students’ understanding of the particulate nature of matter and chemical bonding so as to identify possible associations between students’ understandings of the two concepts. The instrument was administered to 260 Grades 9 and 10 students (15–16 years old) from a secondary school in Singapore. Analysis of students’ responses revealed several alternative conceptions about the two concepts. In addition, analysis of six pairs of items suggested that students’ limited understanding of the particulate nature of matter influenced their understanding of chemical bonding. The findings provide useful information for challenging students’ alternative conceptions about the particulate nature of matter during classroom instruction in order to enable them to achieve better understanding of chemical bonding.     

Students' reasoning about chemical bonding: The lacuna of repulsion

This article concerns a lacuna in chemistry students' reasoning about chemical bonding. Although chemistry students are familiar with the charges that make up the atom––both positive and negative––they refer only to the attraction between unlike charges. Specifically, they ignore the repulsion between the positive nuclei. We named this disregard of repulsion the lacuna of repulsion. Repulsion is a crucial component in the force-based explanation of chemical bonding, presenting the bond as a dynamic equilibrium between attraction and repulsion electrical forces. We noticed this lacuna incidentally while interviewing chemistry students for a bigger project aimed at supporting students in understanding the force-based explanation of chemical bonding. This article describes our systematic qualitative study of the lacuna of repulsion and its impact on mental models of 23 high school chemistry students. Our findings show that students use six mental models, most of them built upon each other. Beginning from a simple mental model that describes the chemical bond as electrons, continuing with the including attraction forces, and completing with repulsion and a dynamic view of the bond. Only when one considers both attraction and repulsion forces and understands the dynamic balance between them is it possible to build the force-based dynamic mental model of chemical bonding.     

Understandings and misunderstandings of eighth graders of five chemistry concepts found in textbooks

The research reported in this study was designed to answer three questions: (a) What misconceptions do eighth grade students have concerning the chemistry concepts from their textbooks. (b) How is reasoning ability related to misconceptions concerning chemistry concepts. (c) How effective are textbooks in teaching an understanding of chemistry concepts? Five chemistry concepts were used in the study: chemical change, dissolution, conservation of atoms, periodicity, and phase change. Problems concerning the five concepts were given to 247 eighth-grade students in order to assess the students' degree of understanding of chemistry concepts and to identify specific misconceptions. Two pencil-and-paper Piaget-type tasks were used to assess intellectual level. A comparison of intellectual level and scores on the chemistry concepts showed moderate correlations. However, the small number of formal operational students in the sample makes these results inconclusive. A study of the level of understanding of the five chemistry concepts and the nature of the misconceptions held by students indicate a general failure of textbooks to teach a reasonable understanding of chemistry concepts.     

Dynamic processes of conceptual change: Analysis of constructing mental models of chemical equilibrium

The purpose of this study was to investigate students' mental models of chemical equilibrium using dynamic science assessments. Research in chemical education has shown that students at various levels have misconceptions about chemical equilibrium. According to Chi's theory of conceptual change, the concept of chemical equilibrium has constraint‐based features (e.g., random, simultaneous, uniform activities) that might prevent students from deeply understanding the nature of the concept of chemical equilibrium. In this study, we examined how students learned and constructed their mental models of chemical equilibrium in a cognitive apprenticeship context. Thirty 10th‐grade students participated in the study: 10 in a control group and 20 in a treatment group. Both groups were presented with a series of hands‐on chemical experiments. The students in the treatment group were instructed based on the main features of cognitive apprenticeship (CA), such as coaching, modeling, scaffolding, articulation, reflection, and exploration. However, the students in the control group (non‐CA group) learned from the tutor without explicit CA support. The results revealed that the CA group significantly outperformed the non‐CA group. The students in the CA group were capable of constructing the mental models of chemical equilibrium—including dynamic, random activities of molecules and interactions between molecules in the microworld—whereas the students in the non‐CA group failed to construct similar correct mental models of chemical equilibrium. The study focuses on the process of constructing mental models, on dynamic changes, and on the actions of students (such as self‐monitoring/self‐correction) who are learning the concept of chemical equilibrium. Also, we discuss the implications for science education. © 2002 Wiley Periodicals, Inc. J Res Sci Teach 39: 688–712, 2002     

Drops of water and of soap solution: Students' constraining mental models of the nature of matter

This study investigates how 25 junior high school students employed their bodies of knowledge and responded to problem cues while individually performing a science experiment and reasoning about a drops phenomenon. Line‐by‐line content analysis conducted on students' written ad hoc explanations aimed to reveal students' concepts and their relations within their explanations, and to construe students' mental models for the science phenomenon based on level of specification, models' correspondence with scientific claims, macro versus micro view of matter, and type of evidence used. We then inferred four types of knowledge representations for the nature of matter. Findings are discussed in terms of implications for science teaching. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 970–993, 2004     

Mapping undergraduate chemistry students' epistemic ideas about models and modeling

Developing and using scientific models is an important scientific practice for science students. Undergraduate chemistry curricula are often centered on established disciplinary models, and assessments typically provide students with opportunities to use these models to predict and explain chemical phenomena. However, traditional curricula generally provide few opportunities for students to consider the epistemic nature of models and the process of modeling. To gain a sense of how introductory chemistry students understand model changeability, model multiplicity, the evaluation of models, and the process of modeling, we use a construct-mapping approach to characterize the sophistication of students' epistemic knowledge of models and modeling. We present a set of four related construct maps that we developed based on the work of other scholars and empirically validated in an undergraduate introductory chemistry setting. We use the construct maps to identify themes in students' responses to an open-ended survey instrument, the models in chemistry survey, and discuss the implications for teaching.     

Emergence, Supervenience, and Introductory Chemical Education

In learning chemistry at the entry level, many learners labor under misconceptions about the subject matter that are so fundamental that they are typically never addressed. A fundamental misconception in chemistry appears to arise from an adding of existing phenomenal concepts to newly-acquired chemical concepts, so that beginning learners think of chemical entities as themselves having the very same ‘macro’ properties that we observe through the senses. Those who teach or practice chemistry never acquire these misconceptions because they were able to naturally pick up the nature of the subject to begin with. But as a result, they remain unaware of the foundational assumptions and understanding that they operate with and that many beginning learners persistently lack. Thus, a systematic picture of the workings of chemical theory as they relate to observable phenomena needs to be elucidated so that the attention of chemical educators is drawn to the fundamental understanding of the subject that they already possess and that beginning learners of chemistry lack, so that beginning learners can be given the opportunity to gain an understanding of how chemical explanations are in general related to observable phenomena. The ‘layered’ way in which chemical and physical entities are related to each other within chemical theory can also be clarified in this way. To afford this picture, the philosophical concepts of supervenience and emergence are explained and applied to chemistry, as philosophers of chemistry have already done. The result provides a model for teaching chemistry that, if consistently applied, has the potential to greatly enhance fundamental understanding of the subject matter.     

The role of submicroscopic and symbolic representations in chemical explanations

Chemistry is commonly portrayed at three different levels of representation – macroscopic, submicroscopic and symbolic – that combine to enrich the explanations of chemical concepts. In this article, we examine the use of submicroscopic and symbolic representations in chemical explanations and ascertain how they provide meaning. Of specific interest is the development of students' levels of understanding, conceived as instrumental (knowing how) and relational (knowing why) understanding, as a result of regular Grade 11 chemistry lessons using analogical, anthropomorphic, relational, problem‐based, and model‐based explanations. Examples of both teachers' and students' dialogue are used to illustrate how submicroscopic and symbolic representations are manifested in their explanations of observed chemical phenomena. The data in this research indicated that effective learning at a relational level of understanding requires simultaneous use of submicroscopic and symbolic representations in chemical explanations. Representations are used to help the learner learn; however, the research findings showed that students do not always understand the role of the representation that is assumed by the teacher.     

Multidimensional analysis system for quantitative chemistry problems: Symbol,macro, micro,and process aspects

There is a consensus regarding the fact that students encounter difficulties in understanding scientific concepts, such as the particulate nature of matter, the mole, and the interpretation of chemical symbols. Researchers and practitioners have been looking for teaching methods to improve students' understanding of quantitative chemistry and their ability to solve related problems. This study describes the Multidimensional Analysis System (MAS), an approach to constructing, classifying, and analyzing quantitative chemistry problems. MAS enables classification based on complexity and transformation levels of a quantitative problem. We define three transformation levels: symbol ? macro, symbol ? micro, and symbol ? process. Applying this framework to teaching and research, we investigated the relationships between MAS‐classified chemistry problems and student achievement in solving these problems. The research population, 241 high school chemistry students, studied problem solving according to MAS for 9 weeks; the control group studied the same topic for the same duration in the traditional way. Student achievement was sorted by mathematics level and gender. We found that the success rate of the entire student population in solving these problems decreased as the problem difficulty increased. Experimental group students scored significantly higher than their control group peers. The improvement in student achievement was significantly dependent on the pretest score and the mathematics level, and independent of gender. Students who studied mathematics in the basic level benefited significantly more from MAS‐based teaching than their peers, whose mathematics level was advanced. Based on the research findings, we recommend applying the multidimensional analysis approach while teaching quantitative problems in chemistry. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 278–302, 2003     

Fostering radical conceptual change through dual‐situated learning model

This article examines how the Dual‐Situated Learning Model (DSLM) facilitates a radical change of concepts that involve the understanding of matter, process, and hierarchical attributes. The DSLM requires knowledge of students' prior beliefs of science concepts and the nature of these concepts. In addition, DSLM also serves two functions: it creates dissonance with students' prior knowledge by challenging their epistemological and ontological beliefs about science concepts, and it provides essential mental sets for students to reconstruct a more scientific view of the concepts. In this study, the concept “heat transfer: heat conduction and convection,” which requires an understanding of matter, process, and hierarchical attributes, was chosen to examine how DSLM can facilitate radical conceptual change among students. Results show that DSLM has great potential to foster a radical conceptual change process in learning heat transfer. Radical conceptual change can definitely be achieved and does not necessarily involve a slow or gradual process. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 142–164, 2004     

How Students Attempt to Reduce Abstraction in the Learning of Mathematics and in the Learning of Computer Science

This article focuses on ion and ways in which students cope with abstraction. The article has two goals: first, it illustrates how the theme of reducing abstraction (Hazzan, 1999) is useful for analyzing students' thinking about abstract concepts in mathematics and in computer science; second, it demonstrates how theories based on mathematics education research can be applied to analyzing students' understanding of computer science concepts. The main section of the article analyzes the understanding of concepts from four fields – abstract algebra, computability, data structures and differential equations – through the lens of reducing abstraction. The analysis shows that a wide range of cognitive phenomena can be explained by one theoretical framework.     

The influence of web‐based chemistry learning on students' perceptions,attitudes, and achievements

The goal of this study was to investigate whether integrating a website into chemistry teaching influences 10th‐grade students' perceptions of the classroom learning environment, their attitudes regarding the relevance of chemistry, and their understanding of the concept of chemical bonding. Two groups participated in this study: an experimental group and a comparison group. The main study was conducted during the academic year 2005. The teachers in the experimental group were asked to implement four relevant activities from the website that was developed, all dealing with the concept of chemical bonding. Quantitative tools of the study included: A Chemistry Classroom Web‐Based Learning Environment Inventory to assess students' perceptions regarding the relevance of chemistry to their life and attitude towards chemistry studies, a feedback questionnaire that examined the students' response after performing the website activities, and an achievement test that assessed their knowledge and understanding of the concept of chemical bonding. We found that the experimental group outperformed the comparison group significantly in most of the research categories. This led us to conclude that the web‐based learning environment has potential to enhance the comprehension of chemistry concepts, students' attitudes and interests and to increase students' awareness regarding the relevant aspects of chemistry to daily life.     

Effects of Combined Hands-on Laboratory and Computer Modeling on Student Learning of Gas Laws: A Quasi-Experimental Study

Based on current theories of chemistry learning, this study intends to test a hypothesis that computer modeling enhanced hands-on chemistry laboratories are more effective than hands-on laboratories or computer modeling laboratories alone in facilitating high school students' understanding of chemistry concepts. Thirty-three high school chemistry students from a private all-girl high school in northeastern United States were divided into two groups to participate in a quasi-experimental study. Each group completed a particular sequence of computer modeling and hands-on laboratories plus pre-test and post-tests of conceptual understanding of gas laws. Each group also completed a survey of conceptions of scientific models. Non-parametric tests, i.e. Friedman's one-way analysis of ranks and Wilcoxon's signed ranks test, showed that the combined computer modeling and hands-on laboratories were more effective than either computer simulations or hands-on laboratory alone in promoting students' conceptual understanding of the gas law on the relationship between temperature and pressure. It was also found that student conception of scientific models as replicas is statistically significantly correlated with students' conceptual understanding of the particulate model of gases. The findings mentioned earlier support the recent call for model-based science teaching and learning in chemistry.     

Student affect and conceptual understanding in learning chemistry

This study explores the relationship between affective and cognitive variables in grade 9 chemistry students (n = 73). In particular, it explores how students' situational interest, their attitudes toward chemistry, and their chemistry‐specific self‐concept influence their understanding of chemistry concepts over the course of a school year. All affective variables were assessed at two time points: at the middle of the first semester of grade 9, and at the end of the second semester of grade 9, and then related to students' postinstructional understanding of chemical concepts. Results reveal that none of the affective variables measured at the earliest time point have a significant direct effect on postinstructional conceptual understanding. Looking at the different affective variables as intermediary constructs, however, reveals a pattern in which self‐concept and situational interest measured at the middle of grade 9 contribute to self‐concept measured at the end of grade 9, which in turn, has a positive, significant effect on students' postinstructional conceptual understanding. These results reveal the importance of a strong and positive self‐concept, the feeling of doing well in the chemistry class, for developing a meaningful understanding of scientific concepts. © 2006 Wiley Periodicals, Inc. J Res Sci Teach 44: 908–937, 2007     

Proofs produced by secondary school students learning geometry in a dynamic computer environment

As a key objective, secondary school mathematics teachers seek to improve the proof skills of students. In this paper we present an analytic framework to describe and analyze students' answers to proof problems. We employ this framework to investigate ways in which dynamic geometry software can be used to improve students' understanding of the nature of mathematical proof and to improve their proof skills. We present the results of two case studies where secondary school students worked with Cabri-Géeomèetre to solve geometry problems structured in a teaching unit. The teaching unit had theaims of: i) Teaching geometric concepts and properties, and ii) helping students to improve their conception of the nature of mathematical proof and to improve their proof skills. By applying the framework defined here, we analyze students' answers to proof problems, observe the types of justifications produced, and verify the usefulness of learning in dynamicgeometry computer environments to improve students' proof skills.     

A window into thinking: Using student writing to understand conceptual change in science learning

This study, conducted in an inner-city middle school, followed the conceptual changes shown in 25 students' writing over a 12-week science unit. Conceptual changes for 6 target students are reported. Student understanding was assessed regarding the nature of matter and physical change by paper-and-pencil pretest and posttest. The 6 target students were interviewed about the goal concepts before and after instruction. Students' writing during lesson activities provided qualitative data about their understandings of the goal concepts across the science unit. The researcher constructed concept maps from students' written statements and compared the maps across time to assess changes in the schema of core concepts, complexity, and organization as a result of instruction. Target students' changes were studied in detail to determine patterns of conceptual change. After patterns were located in target students' maps, the remaining 19 students' maps were analyzed for similar patterns. The ideas that students identified in their writing showed changes in central concepts, complexity, and organization as the lessons progressed. When instructional events were analyzed in relation to students' demonstrated ideas, understanding of the goal conceptions appeared in students' writing more often when students had opportunities to explain their new ideas orally and in writing.     

Promoting understanding of chemical representations: Students' use of a visualization tool in the classroom

Many students have difficulty learning symbolic and molecular representations of chemistry. This study investigated how students developed an understanding of chemical representations with the aid of a computer‐based visualizing tool, eChem, that allowed them to build molecular models and view multiple representations simultaneously. Multiple sources of data were collected with the participation of 71 eleventh graders at a small public high school over a 6‐week period. The results of pre‐ and posttests showed that students' understanding of chemical representations improved substantially (p < .001, effect size = 2.68‐. The analysis of video recordings revealed that several features in eChem helped students construct models and translate representations. Students who were highly engaged in discussions while using eChem made referential linkages between visual and conceptual aspects of representations. This in turn may have deepened their understanding of chemical representations and concepts. The findings also suggest that computerized models can serve as a vehicle for students to generate mental images. Finally, students demonstrated their preferences of certain types of representations and did not use all types of three‐dimensional models interchangeably. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 821–842, 2001