Correct Interpretation of Chemical Diagrams Requires Transforming from One Level of Representation to Another

Volunteer non-major chemistry students taking an introductory university chemistry course (n = 17) were interviewed about their understanding of a variety of chemical diagrams. All the students’ interviewed appreciated that diagrams of laboratory equipment were useful to show how to set up laboratory equipment. However students’ ability to explain specific diagrams at either the macroscopic or sub-microscopic level varied greatly. The results highlighted the poor level of understanding that some students had even after completing both exercises and experiments using the diagrams. The connection between the diagrams of the macroscopic level (equipment, chemicals), the sub-microscopic level (molecular) and the symbolic level (equations) was not always considered explicitly by students. The results indicate a need for chemical diagrams to be used carefully and more explicitly to ensure learner understanding. Correspondingly, students need to interpret visual chemical diagrams using meta-visualization skills linking the various levels of representation, and appreciating the role of the diagrams in explanations need to be developed.     

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.     

A jigsaw cooperative learning application in elementary science and technology lessons: physical and chemical changes

Cooperative learning is an active learning approach in which students work together in small groups to complete an assigned task. Students commonly find the subject of ‘physical and chemical changes’ difficult and abstract, and thus they generally have many misconceptions about it.

Purpose

This study aimed to investigate the effects of jigsaw cooperative learning activities developed by the researchers on sixth grade students’ understanding of physical and chemical changes.

Sample

Participants in the study were 61 sixth grade students in a public elementary school in Izmir, Turkey.

Design and methods

A pre-test and post-test experimental design with a control group was used, and students were randomly assigned to the experimental and control groups. Instruction of the subject was conducted via jigsaw cooperative learning in the experimental group and via teacher-centered instruction in the control group. During the jigsaw process, experimental group students studied the subjects of changes of state, changes in shape and molecular solubility from physical changes, and acid–base reactions, combustion reactions and changes depending on heating from chemical changes in their jigsaw groups.

Results

The concept test results showed that jigsaw cooperative learning instruction yielded significantly better acquisition of scientific concepts related to physical and chemical changes, compared to traditional learning. Students in the experimental group had a lower proportion of misconceptions than those in the control group, and some misconceptions in the control group were identified for the first time in this study.

Conclusions

Jigsaw cooperative learning is an effective teaching technique for challenging sixth grade students’ misconceptions in the context of physical and chemical changes, and enhancing their motivation, learning achievements, self-confidence and willingness in the science and technology lesson. This technique could be applied to other chemistry subjects and other grade levels.     

Classification of Chemical Substances using Particulate Representations of Matter: An analysis of student thinking

We applied a mixed‐method research design to investigate the patterns of reasoning used by novice undergraduate chemistry students to classify chemical substances as elements, compounds, or mixtures based on their particulate representations. We were interested in the identification of the representational features that students use to build a classification system, and in the characterization of the thinking processes that they follow to group substances in different classes. Students in our study used structural and chemical composition features to classify chemical substances into elements, compounds, and mixtures. Many of the students’ classification errors resulted from strong mental associations between concepts (e.g., atom–element, molecule–compound) or from lack of conceptual differentiation (e.g., compound–mixture). Strong concept associations led novice students to reduce the number of relevant features used to differentiate between substances, while the inability to discriminate between two concepts (conceptual undifferentiation) led them to pay too much attention to irrelevant features during the classification tasks. Comparisons of the responses to classification tasks of students with different levels of expertise in chemistry indicate that some of these naïve patterns of reasoning may be strengthened by, rather than weakened by, training in the discipline.     

Explanations and Teleology in Chemistry Education

It has been commonly assumed that teleological explanations are unnecessary and have no place in the physical sciences. However, there are indications that teleology is fairly common in the instructional explanations of teachers and students in chemistry classrooms. In this study we explore the role and nature of teleological explanations and the conditions that seem to warrant their use in chemistry education. We also analyse the learning implications of developing explanations of chemical phenomena within a teleological stance. Our study is based on the qualitative analysis of the instructional explanations presented in traditional chemistry textbooks used in the United States. Our results indicate that teleological explanations are in fact present in these textbooks and help provide an explanatory reason for the occurrence of chemical transformations. Their use is tightly linked to the existence of a rule, principle, or law that governs the behaviour of a chemical system, and that explicitly or implicitly implies the minimisation or maximisation of some intrinsic property. This law or principle tends to provide a sense of preferred direction in the evolution of a transformation. Although teleological explanations seem to have heuristic pedagogical value in chemistry education, they may also lead students to develop alternative conceptions and unwarranted overgeneralisations.     

Exploring How Different Features of Animations of Sodium Chloride Dissolution Affect Students’ Explanations

Animations of molecular structure and dynamics are often used to help students understand the abstract ideas of chemistry. This qualitative study investigated how the features of two different styles of molecular-level animation affected students’ explanations of how sodium chloride dissolves in water. In small group sessions 18 college-level general chemistry students dissolved table salt in water, after which they individually viewed two animations of salt dissolution. Before and after viewing each animation the participants provided pictorial, written, and oral explanations of the process at the macroscopic and molecular levels. The students then discussed the animations as a group. An analysis of the data showed that students incorporated some of the microscopic structural and functional features from the animations into their explanations. However, oral explanations revealed that in many cases, participants who drew or wrote correct explanations did not comprehend their meanings. Students’ drawings may have reflected only what they had seen, rather than a cohesive understanding. Students’ explanations given after viewing the animations improved, but some prior misconceptions were retained and in some cases, new misconceptions appeared. Students reported that they found the animations useful in learning; however, they sometimes missed essential features when they watched the animation alone.     

Compounding Confusion? When Illustrative Practical Work Falls Short of its Purpose—A Case Study

Illustrative practical work is commonly used in chemistry education to enrich students?? understandings of chemical phenomena. However, it is possible that such practical work may not serve to foster understanding but rather cause further confusion. This paper reports the struggles experienced by a group of senior (Year 12) secondary chemistry students as they sought to understand redox chemical concepts involved in the reactions occurring when steel wool is added to copper sulfate solution. The results showed that the students lacked the skills required to make accurate observations during the practical work. Nor were they able to link the observed phenomena with previously taught redox concepts. The paper also presents possible ways to overcome the difficulties encountered by students as they move between macroscopic and submicroscopic levels of representation of redox reactions.     

How Do Chemistry Teachers Deal with Students' Incorrect/Undesired Responses to Oral Classroom Questions? Exploring Effective Feedback Practices

In this paper, chemistry teachers’ reactions/behavior or actions following students’ undesired, unexpected or incorrect responses/answers to the posed teacher oral questions are reported. This study which was carried out in Tanzania in Iringa Municipality involved three chemistry teachers teaching in three different secondary schools. Actual teaching situations of the three teachers were recorded, transcribed, and analyzed interpretively. We also performed semi-structured interviews with these teachers to bring forth the teachers’ inherent perceptions about their practice in relation to what was observed of the teachers’ individual actual teaching situations. Up to eight different forms of teachers’ responses or reactions to students’ undesired responses or incorrect answers are discussed with respect to how each is perceived to either positively or negatively affect students’ progressive learning. From the study, productive questioning is affected by teachers’ inability to effectively use classroom powers to trigger students’ thinking, as well as not being able to use students’ varied views to achieve the set learning goals. Instead of using their power strategies to facilitate students’ engagement with the scientific matter, the teachers used their classroom powers to guard themselves against classroom insecurities during the teaching process, such as preventing students from questioning their subject knowledge competencies.

     

Scientific explanations and piagetian operational levels

Explaining natural phenomena is an important goal in science teaching. A logical analysis reveals that causal explanations exhibit formal operational structures in that they consist of implication statements chained together through transitive reasoning. It was hypothesized in the present study that individuals who do not reason formally will have difficulty in learning explanations presented in instruction. To test this hypothesis, the effect of levels of operational thought on the explanations which ninth-grade (n = 26) and college (n = 40) physical science students reconstructed after instruction was investigated. Subjects in the study were classified through Piagetian tests as concrete or formal operational. Both concrete and formal subjects were successful in recalling explanations requiring the chaining of two implication statements. Formal operational subjects performed significantly better than concrete operational subjects in three of the four tests of the reconstruction of complex explanations requiring the chaining of six implication statements. In teaching complex causal explanations to students at the concrete operational level, it is suggested that teachers be prepared to furnish some external structuring which the students can rely on in logically relating the various propositions of the explanation to one another.     

An Evaluation of a Teaching Intervention to Promote Students’ Ability to Use Multiple Levels of Representation When Describing and Explaining Chemical Reactions

Students are generally known to memorise and regurgitate chemical equations without sufficient understanding of the changes that occur at the particulate level. In addition, they often fail to recognise the significance of the symbols and formulas that are used to represent chemical reactions. This article describes an evaluation of the ability of 65 Grade 9 students (15–16 years old) from a Singapore secondary school to describe and explain seven types of chemical reactions using macroscopic, submicroscopic and symbolic representations. The study was conducted over nine months using a supplementary teaching program with particular emphasis on the use of multiple levels of representation to describe and explain chemical reactions. Students’ proficiency in the use of multiple levels of representation was assessed at the end of the course using a two-tier multiple-choice diagnostic instrument that was previously developed by the authors. In order to evaluate the efficacy of the instructional program, the instrument was also administered to another group of 76 students who were not involved in the supplementary instructional program. The efficacy of the program was evident from the significantly improved scores on the diagnostic instrument of the former group of students. In addition, several student conceptions in the use of multiple levels of representation were identified that could assist teachers in their planning and implementation of classroom instruction.     

Development of a Learning Progression for the Formation of the Solar System

This study describes the process of defining a hypothetical learning progression (LP) for astronomy around the big idea of Solar System formation. At the most sophisticated level, students can explain how the formation process led to the current Solar System by considering how the planets formed from the collapse of a rotating cloud of gas and dust. Development of this LP was conducted in 2 phases. First, we interviewed middle school, high school, and college students (N?=?44), asking them to describe properties of the current Solar System and to explain how the Solar System was formed. Second, we interviewed 6th-grade students (N?=?24) before and after a 15-week astronomy curriculum designed around the big idea. Our analysis provides evidence for potential levels of sophistication within the hypothetical LP, while also revealing common alternative conceptions or areas of limited understanding that could form barriers to progress if not addressed by instruction. For example, many students' understanding of Solar System phenomena was limited by either alternative ideas about gravity or limited application of momentum in their explanations. Few students approached a scientific-level explanation, but their responses revealed possible stepping stones that could be built upon with appropriate instruction.     

Emergence,Learning Difficulties,and Misconceptions in Chemistry Undergraduate Students’ Conceptualizations of Acid Strength

Philosophical debates about chemistry have clarified that the issue of emergence plays a critical role in the epistemology and ontology of chemistry. In this article, it is argued that the issue of emergence has also significant implications for understanding learning difficulties and finding ways of addressing them in chemistry. Particularly, it is argued that many misconceptions in chemistry may derive from students’ failure to consider emergence in a systemic manner by taking into account all relevant factors in conjunction. Based on this argument, undergraduate students’ conceptions of acids, and acid strength (an emergent chemical property) were investigated and it was examined whether or not they conceptualized acid strength as an emergent chemical property. The participants were 41 third- and fourth-year undergraduate students. A concept test and semi-structured interviews were used to probe students’ conceptualizations and reasoning about acid strength. Findings of the study revealed that the majority of the undergraduate students did not conceptualize acid strength as an emergent property that arises from interactions among multiple factors. They generally focused on a single factor to predict and explain acid strength, and their faulty responses stemmed from their failure to recognize and consider all factors that affect acid strength. Based on these findings and insights from philosophy of chemistry, promoting system thinking and epistemologically sound argumentative discourses among students is suggested for meaningful chemical education.     

Students' Ideas about Reaction Rate and its Relationship with Concentration or Pressure

This cross‐sectional study identifies key conceptual difficulties experienced by upper secondary school and pre‐service chemistry teachers (N = 191) in the area of reaction rates. Students' ideas about reaction rates were elicited through a series of written tasks and individual interviews. In this paper, students' ideas related to reaction rate and its relationship with concentration or pressure are discussed. Evidence is presented to support the following claims. First, school students tended to use “macroscopic” modelling rather than using “particulate” and/or “mathematical” modelling. By contrast, undergraduates were more likely to provide explanations based upon theoretical models and entities within established chemical ideas. Nevertheless, second, they had conceptual difficulties in making transformation within and across different theoretical models. Finally, students did not generally use a scientifically acceptable concept of reaction rate across contexts. Although an acceptable concept may have been used in one context, incorrect ideas may, nonetheless, have been used in other contexts. However, undergraduates' responses were less affected by context. Several conceptual difficulties exhibited by school students persisted among undergraduates. Some possible implications for planning the curriculum and teaching are proposed in the light of the results.     

The how's and why's of biological change: How learners neglect physical mechanisms in their search for meaning

This study describes the trends in students' explanations of biological change in organisms. A total of 96 student volunteers (8 students from each of 2nd, 5th, 8th, and 12th grades from 3 localities) were interviewed individually and each student was presented a series of graphics depicting natural phenomena. Students' explanations to questions of how something occurred were assigned to one of three categories (responses addressing how something occurred, why something occurred, and 'I don't know'). While the number of responses in each category was roughly equivalent in prominence across grade levels, the majority of students were unable to offer a causal explanation of how a phenomena occurred. An unexpected phenomenon was the students' predilection to redirect the interview question so they could answer them. If asked a how question, as they were in every interview instance, 32% the students answered with a 'why' response. The way biology is taught, the structure of biology or/and how we learn it could shed some light into this phenomenon and has implications for science educators.     

Learning Processes in Chemistry: Drawing Upon Cognitive Resources to Learn About the Particulate Structure of Matter

This article explores 11- to 16-year-old students' explanations for phenomena commonly studied in school chemistry from an inclusive cognitive resources or knowledge-in-pieces perspective that considers that student utterances may reflect the activation of knowledge elements at a range of levels of explicitness. We report 5 themes in student explanations that we consider to derive from implicit knowledge elements activated in cognition. Student thinking in chemistry has commonly been examined from a misconceptions or alternative conceptions/frameworks perspective, in which the focus has been on the status of learners' explicit conceptions. This approach has been valuable, but it fails to explain the origins or nature of the full range of alternative ideas reported. In physics education, the cognitive resources perspective has led to work to characterize implicit knowledge elements—described as phenomenological primitives (p-prims)—that provide learners with an intuitive sense of mechanism. School chemistry offers a complementary knowledge domain because of its focus on the nature of materials and its domination by theoretical models that explain observable phenomena in terms of emergent properties of complex ensembles of “quanticles” (molecules, ions, electrons, atoms, etc.) The themes reported in this study suggest a need to recognize primitive knowledge elements beyond those reported from physics education and suggest that some previously characterized p-prims may be better considered to derive from more broadly applicable intuitive knowledge elements.     

Explanations from intra- and inter-group discourse: Students building knowledge in the science classroom

This article discusses the relation and patterns of intra- and inter-group discourse as middle school students explain particular phenomena. We present a framework of the dynamic process involved in generating collaborative knowledge. Our focus is on connecting students' thinking and experience with science concepts and explanations. Using the perspective of learning as a social activity, we are interested in science teaching that engages students in collaborative inquiry as a means for learning science content. Specifically, we examine the role of shared inquiry and the nature of consensus-building in students' development of explanations from a collaborative knowledge-building stance. Student discourse, in small (intra-group) and large (inter-group) contexts, is examined as an explicit mode of inquiry. While additional study is needed, we contend these two forms of discourse (constructive and generative; dialectic and persuasive) effectively promote progressive discourse and thereby facilitate shared coherent explanations of phenomena. If we now consider dialectics rather than method as the logic of science, the whole image changes because of the essential, constitutive role played by interlocutors. Due to this role, science becomes a game with three players: an inquiring mind, or, more realistically, a group of the communityC ₁, natureN, and another group of the communityC ₂. (Pera, 1994, p. 133).     

Research report

We examined ninth-grade students' explanations of chemical reactions using two forms of an open-ended essay question during a learning cycle. One form provided students with key terms to be used as 'anchors' upon which to base their essay, whereas the second form did not. The essays were administered at three points: pre-learning cycle, post-concept application, and after additional concept application activities. Students' explanations were qualitatively examined and grouped according to common patterns representing their understandings or misunderstandings. Findings indicated that more misunderstandings were elicited by the use of key terms as compared to the non-use of key terms in the pre-test. Misunderstandings in the key term essay responses generally involved the misuse of these terms and their association with the concept. Findings also indicated significant positive shifts in students' understanding over the learning cycle. No perceptible increase in understanding occurred after additional application activities. Differences in gender were observed, with females showing equal or greater understanding compared to males, contradicting reports that males typically outperform females in the physical sciences and supporting the need to reconstruct assessment techniques to better reveal the conceptual understandings of all students.