Understanding what is possible across a career: professional identity development beyond transition to teaching

Professional identity surfaces repeatedly as an important underlying factor in teacher development. A sequential explanatory mixed methods design was used to investigate identity development in terms of teachers’ expected and feared possible selves. Teachers (n = 120) representing three career groups (prospect, new, and experienced) participated. The findings reveal differences in possible selves which are detectable based on career group. New teachers exhibited a greater focus on task self-concepts; prospective teachers expressed both task and quality possible selves; and experienced teachers expressed identities more concerned about the quality-focused ones. Our findings also reveal a potential transition path in professional identity development.     

Cognitive conflict as a teaching strategy in solving chemistry problems: A dialectic–constructivist perspective

The main objective of this study was to evaluate the effect of teaching experiments within a dialectic-constructivist framework based on the following considerations: (a) Cognitive conflicts used in the teaching experiments must be based on problem-solving strategies that students find relatively convincing: (b) after having generated a cognitive conflict, it is essential that the students be provided with an experience that could facilitate the resolution of the conflict; and (c) the teaching strategy developed is used by an interactive constructivist approach within an intact classroom. The study was based on two sections of freshman students who had registered for Chemistry I at the Universidad de Oriente, Venezuela. One of the sections was randomly designated as the control group and the other as the experimental group. To introduce cognitive conflict, the experimental group was exposed to two teaching experiments dealing with stoichiometry problems based on the concept of limiting reagent. Students in the control group were exposed to the same problems—however, without the cognitive conflict teaching experiments format. To evaluate the effect of the teaching experiments, both groups were evaluated on five different problems at different intervals during the semester, referred to as posttests. All posttests formed part of the regular evaluation of the students. Results obtained show the advantage of the experimental group on four of the posttests. It is concluded that the experimental treatment was effective in improving performance on the immediate posttests. It was observed that some students protect their core belief [see Lakatos, I. (1970). Falsification and the methodology of scientific research programmes. In I. Lakatos & A. Musgrave (Eds.), Criticism and the growth of knowledge (pp. 91–196). Cambridge: Cambridge University Press] in stoichiometry (establishing equivalent relations between different elements or compounds) by ignoring the conflicting data, just as conflicting (anomalous) data do not necessarily convince a scientist to abandon a particular theory.     

How in Spite of the Rhetoric,History of Chemistry has Been Ignored in Presenting Atomic Structure in Textbooks

Recent research in science education has recognized the importance of history and philosophy of science. This study has the following objectives:(a) To show how the importance of history of chemistry has been recognized in theclassroom, starting from the 1920s to the present; (b) How criteria based on history andphilosophy of science can be used to evaluate presentation of atomic structure in generalchemistry textbooks; (c) Comparison of the new (1970–1992) and old textbooks (1929–1967)with respect to the presentation of atomic structure. Results obtained show thatmost of the new and old textbooks not only ignore the history and philosophy of sciencebut also present experimental findings as a `rhetoric of conclusions'. It isconcluded that such presentations are not conducive towards a better understanding of scientificprogress. It is suggested that history and philosophy of science can be introduced in theclassroom not necessarily through formal courses in the history of chemistry or commentsand anecdotes, but rather by incorporating the `heuristic principles' that guided thescientists to elaborate their theories.     

The Oil Drop Experiment: Do Physical Chemistry Textbooks Refer to its Controversial Nature?

Most general chemistry textbooks consider the oil drop experiment as a classic experiment, characterized by its simplicity and precise results. A review of the history and philosophy of science literature shows that the experiment is difficult to perform (even today!) and generated a considerable amount of controversy. Acceptance of the quantization of the elementary electrical charge was preceded by a bitter dispute between R.A. Millikan and F. Ehrenhaft, that lasted for many years (1910–1925). The objective of this study was to investigate whether physical chemistry textbooks refer to the controversial nature of the experiment. Based on six criteria developed previously, 28 physical chemistry textbooks were evaluated. Analysis of the texts using six identified criteria demonstrated that the textbooks neither referred to the controversial nature of the experiment nor recognized the difficulty of the experimental procedure. Only a few texts even attempted to include any discussion of the history or philosophy of the experiment. The instructor of a physical chemistry course could include aspects of the Millikan–Ehrenhaft controversy to motivate classroom discussion and help facilitate an understanding of the role that controversy has in scientific progress.     

Reasoning strategies of students in solving chemistry problems as a function of developmental level,functional M‐capacity and disembedding ability

Achievement in science depends among other factors on hypothetico‐deductive reasoning ability, that is, developmental level of the students. Recent research indicates that the developmental level of students should be studied along with individual difference variables, such as Pascual‐Leone's M‐capacity (information processing) and Witkin's Cognitive Style (disembedding ability). The purpose of this study is to investigate reasoning strategies of students in solving chemistry problems as a function of developmental level, functional M‐capacity and disembedding ability. A sample of 109 freshman students were administered tests of formal operational reasoning, functional M‐capacity, disembedding ability and chemistry problems (limiting reagent, mole, gas laws). Results obtained show that students who scored higher on cognitive predictor variables not only have a better chance of solving chemistry problems, but also demonstrated greater understanding and used reasoning strategies indicative of explicit problem‐solving procedures based on the hypothetico‐deductive method, manipulation of essential information and sensitivity to misleading information. It was also observed that students who score higher on cognitive predictor variables tend to anticipate important aspects of the problem situation by constructing general figurative and operative models, leading to a greater understanding. Students scoring low on cognitive predictor variables tended to circumvent cognitively more demanding strategies and adopt others that helped them to overcome the constraints of formal reasoning, information processing and disembedding ability.     

Portrayal of the History of the Photoelectric Effect in Laboratory Instructions

The literature on the pedagogical aspects of the photoelectric effect as used in the undergraduate student laboratory shows that little research has been done in this area. Our current study is an analysis of the instructions in 38, electronically published laboratory manuals for the photoelectric effect. The analyses were based on history and philosophy of science criteria that we had developed for evaluating the presentation of the photoelectric effect in introductory, university-physics textbooks. The results show that writers of laboratory instructions do not pay sufficient attention to the relevant background for the photoelectric effect. In our study, none of the instructions achieved a score of excellent, only 5% were scored as satisfactory, and only 7% mentioned the various aspects contained in our criteria. These results for our analysis of laboratory instructions are significantly less favorable than those achieved for physics textbooks in our previous study. Based on our work, we recommend that several historical aspects be included in all laboratory instructions for the photoelectric effect.     

Understanding Quantum Numbers in General Chemistry Textbooks

Quantum numbers and electron configurations form an important part of the general chemistry curriculum and textbooks. The objectives of this study are: (1) Elaboration of a framework based on the following aspects: (a) Origin of the quantum hypothesis, (b) Alternative interpretations of quantum mechanics, (c) Differentiation between an orbital and electron density, (d) Differentiation and comparison between classical and quantum mechanics, and (e) Introduction of quantum numbers based on electron density; (2) Formulation of five criteria based on the different aspects (a, b, c, d, and e), and (3) Evaluation of 55 freshman college‐level general chemistry textbooks. Results obtained show: Criterion 1, none of the textbooks described satisfactorily that Planck’s role in the origin of the quantum hypothesis was more at the level of an empirical adjustment, whereas Einstein provided the physical significance of the quantum hypothesis; Criterion 2, few textbooks (two satisfactory and four mentioned) included alternative interpretations of quantum mechanics (e.g., Bohm) and thus ignored that most theories are underdetermined by experimental evidence; Criterion 3, none of the textbooks described satisfactorily that orbitals are mathematical constructs and the shapes of the orbitals (s, p, d, f) are not derived from quantum mechanics but instead from electron density measurements; Criterion 4, although, quantum mechanics approaches classical mechanics as a limiting case, none of the textbooks presented a framework to facilitate transition in student understanding from classical to quantum mechanics (28 textbooks made a simple mention); and Criterion 5, few textbooks (one satisfactory, five mentioned) facilitated the introduction of quantum numbers based on experimental determination of electron density (photoelectron spectrum). It is concluded that the inclusion of these criteria in textbooks can facilitate students’ conceptual understanding of quantum numbers and electron configurations.     

Whither constructivism?—A chemistry teachers’ perspective

Constructivism in science education has been the subject of considerable debate in the science education literature. The purpose of this study was to facilitate chemistry teachers’ understanding that the tentative nature of scientific knowledge leads to the coexistence and rivalries among different forms of constructivism in science education. The study is based on 17 in-service teachers who had registered for a 11-week course on ‘Epistemology of Science Teaching’ as part of their Master's degree program. The course is based on 17 readings drawing on nature of science and a critical evaluation of constructivism. Course activities included written reports, classroom discussions based on participants’ presentations and written exams. Based on the results obtained, it is plausible to suggest that participant teachers experienced the following transitions leading to greater understanding, as they acquired experience with respect to constructivism: (a) Active participation of students as a pre-requisite for change; (b) Different forms of constructivism represent competing and conflicting interpretations of progress in science; (c) Acceptance of the present state of constructivism as a Kuhnian paradigm; (d) Social constructivism as the preferred form of constructivism; (e) Critical appraisal of social constructivism; (f) Despite its popularity, social constructivism does not constitute a Kuhnian paradigm (due to controversies, there is no consensus in the science education community); (g) Contradictions faced by constructivism in science education provide the base for its advance and evolution towards more progressive forms, and hence the need to consider, whither constructivism?     

Neurohumoral alterations and their role in amoebiasis

Amoebiasis is world wide in distribution and continues to be an important Public health problem. Intestinal amoebiasis may be present as dysentery, diarrhea or may stimulate other intra abdominal conditions. Clinical symptoms may not be seen in majority of patients, while amebic cysts are passed in the stool. This single-celled parasite is transmitted to humans via contaminated water and food. Amoebic dysentery can be accompanied by amebic infection of the liver and other organs. The present study was carried out to evaluate the changes in the circulating levels of neurohumors, their metabolizing enzymes and cortisol in these patients both before and after one month of chemotherapy. In the patients of amoebiasis the circulating acetylcholine (ACh), histamine, histaminase, cortisol, 5-Hydroxy tryptamine (serotonin) levels were significnatly enhanced with no change in the Dopamine-beta-hydroxylase (DBH) activity, while the activities of erythrocyte aceytylcholinesterase (AChE) and plasma Monoamine oxidase (MAO) were found decreased in comparison to normal healthy controls. After one month of treatment all the parameters reverted towards their control values, while the level of plasma histaminase remained still significantly high. The normal DBH activity reflects that there is no alteration in the circulating catecholamine levels. while the alteration in the levels of histamine, serotonin and cortisol may be due to the nonspecific response of the body to the stress of the disease and the parasitic infestation.     

Science curriculum and teacher education: The role of presuppositions,contradictions, controversies and speculations vs Kuhn's ‘normal science’

Kuhn (1970) considered textbooks to be good 'pedagogical vehicles' for the perpetuation of ‘normal science’. Collins (2000) has pointed out a fundamental contradiction with respect to what science could achieve (create new knowledge) and how we teach science (authoritarian). Despite the reform efforts, students still have naïve views about the nature of science. Textbook analyses show almost a complete lack of understanding of the role played by presuppositions, contradictions, controversies and speculations in scientific progress. A possible solution to the contradiction pointed out by Collins is provided by the comparison of teaching approaches based on Kuhnian and Lakatosian perspectives of history and philosophy of science. It appears that the Kuhnian approach leaves out what really happens, that is the 'how' and 'why' of scientific progress. On the other hand, the Lakatosian perspective would enable students to understand that scientific progress is subsumed by a process that involves conflicting frameworks (dispute in science, according to Collins, 2000), based on processes that require the elaboration of rival hypotheses and their evaluation in the light of new evidence. It is plausible to suggest that the teacher by 'unfolding' the different episodes (based on historical reconstructions) can emphasize and illustrate how science actually works (tentative, controversial, rivalries, alternative interpretations of the same data), and this will show to the students that they need to go beyond ‘normal science’ as presented in their textbooks.