Mansoor Niaz

From cathode rays to alpha particles to quantum of action: A rational reconstruction of structure of the atom and its implications for chemistry textbooks

Research in science education has recognized the importance of the history and philosophy of science. Given this perspective, it is important to analyze chemistry textbooks, at the freshman college level, to determine the degree to which they deal with recent developments in the history and philosophy of science. This study has the following objectives: (a) elaboration of a framework, based on a rational reconstruction of developments that led to the formulation of atomic models by Thomson, Rutherford, and Bohr; (b) formulation of eight criteria based on the framework that could be useful in the evaluation of chemistry textbooks; and (c) evaluation of the textbooks based on the criteria. Twenty-three textbooks were evaluated on the eight criteria. Results obtained show that most textbooks emphasize experimental details based on observations, leading to the presentation of scientific progress as a rhetoric of conclusions, based on irrevocable truths. Such an understanding lacks the conceptualization of the heuristic principles that led the scientists to design and interpret their experiments. For example, in the case of J. J. Thomsons work, besides the experimental details of cathode ray experiments (emphasized by most textbooks), the “heuristic principle” involved the testing of rival hypotheses, namely a determination of the mass-to-charge ratio would have helped to identify cathode ray particles as an ion or a universal charged particle. Most textbooks presented the experimental details, without the conceptualization that progress in science is based on competing frameworks of understanding that clash in the face of evidence. It is concluded that textbooks should emphasize not only the experimental details but also the “heuristic principles” required to “structure inquiry.”

The Oil Drop Experiment: A Rational Reconstruction of the Millikan-Ehrenhaft Controversy and Its Implications for Chemistry Textbooks.

Research in science education has recognized the importance of history and philosophy of science. Given this perspective, it is important to analyze how general chemistry textbooks interpret Mil- likans oil drop experiment. This study has the following objectives: (a) elaboration of a history and phi- losophy of science framework based on a rational reconstruction of experimental observations that led to the Millikan-Ehrenhaft controversy; (b) formulation of six criteria based on the framework, which could be useful in the evaluation of chemistry textbooks; and (c) evaluation of 31 chemistry textbooks based on the criteria. Results obtained showed that most textbooks lacked a history and philosophy of science framework and did not deal adequately with the following aspects. (a) The Millikan-Ehrenhaft contro- versy can open a new window for students, demonstrating how two well-trained scientists can interpret the same set of data in two different ways. (b) Millikans perseverance with his guiding assumption shows how scientists can overcome difficulties with anomalous data. (c) Millikans methodology illustrates what modern philosophers of science consider important issues of falsification, confirmation, and suspension of disbelief. (d) The experiment is difficult to perform even today, owing to the incidence of a series of variables. (e) Millikans major contribution consists of discovering the experiment to provide confirma- tion for the elementary electrical charge.

A rational reconstruction of the origin of the covalent bond and its implications for general chemistry textbooks

The main objectives of this study are: (i) development of a perspective based on history and philosophy of science considerations (rational reconstruction) in order to understand the postulation of the covalent bond by Lewis; (ii) formulation of four criteria based on the perspective; and (iii) evaluation of 27 textbooks based on the four criteria. Results obtained show that most textbooks lacked a history and philosophy of science perspective and did not deal adequately with the following aspects: (i) Lewiss postulation of the covalent bond in 1916 posed considerable conceptual difficulties; (ii) Lewis used the cubical atom (a hypothetical entity) in order to understand the sharing of electrons in the covalent bond (octet rule); (iii) sharing of electrons had to compete with the transfer of electrons (ionic bond) considered to be the dominant paradigm until about 1920; (iv) postulation of the covalent bond (octet rule) was not an inductive generalization based on stability of the noble gases and the high dissociation energy of the covalent bonds; and (v) Pauli exclusion principle provides a theoretical explanation of the sharing of electrons, just as the cubical atom did previously. It is concluded that the development of the covalent bond does not follow the inductivist process, viz. experimental observations lead to scientific laws which later facilitate the elaboration of explanatory theories.

Performance based on instruction by lecture or by interaction and its relationship to cognitive variable

The performance of two groups of chemistry students in solving stoichiometry problems has been investigated. The control group was taught by traditional lectures, while the treatment group was taught by an interactive technique. We have also examined the effect of various cognitive variables on performance within the two groups. The interactive group was more successful in solving chemistry stoichiometry problems than the lecture group. In both groups, students with better formal reasoning skills (higher GALT scores) performed better than students with lower GALT scores. However, students with lower information‐processing capabilities (lower FIT scores) in the interactive section performed better than students with higher FIT scores. It may be that the interaction encouraged the treatment group to look for strategies which utilize cognitive variables, while the control group may have looked to training. It is interesting that the interactive instruction appears more effective for students who are less ade...

Enhancing thinking skills: Domain specific/ domain general strategies

The main objective of this article is to provide a framework, based on a critical appraisal of the philosophy of science, that could help science educators to choose between domain-specific and domain-general strategies for enhancing the thinking skills of their students. Recent literature has emphasized that one of the most pervasive features of scientific practice is that of gathering evidence by making observations and conducting experiments. Research suggests that children do manifest, in a rudimentary form, the scientific thinking skills of raising causal questions, generating hypotheses and conducting experiments in order to test hypotheses, and that these skills increase progressively with age. It is concluded that we should not in the science classroom, emphasize only domain-specific knowledge. Absence of a single ‘scientific method’ provides the occasion to shift from one method to another, thus facilitating competing frameworks of understanding. Evidence is provided to show that emphasizing domain specific (content) over domain general knowledge is consistent with a Kuhnian perspective of ‘normal science’. On the other hand, adopting the Lakatosian perspective would enable the students to understand that scientific progress goes through a process of conflicting frameworks, based on processes that require elaboration of rival hypotheses and their evaluation. It is concluded that the content-process dichotomy is misleading as the two approaches to teaching science would rather complement each other.

Teaching algorithmic problem solving or conceptual understanding: Role of developmental level, mental capacity, and cognitive style

It has been shown previously that many students solve chemistry problems using only algorithmic strategies and do not understand the chemical concepts on which the problems are based. It is plausible to suggest that if the information is presented in differing formats, the cognitive demand of a problem changes. The main objective of this study is to investigate the degree to which cognitive variables, such as developmental level, mental capacity, and disembedding ability explain student performance on problems which: (1) could be addressed by algorithms or (2) require conceptual understanding. All conceptual problems used in this study were based on a figurative format. The results obtained show that in all four problems requiring algorithmic strategies, developmental level of the students is the best predictor of success. This could be attributed to the fact that these are basically computational problems, requiring mathematical transformations. Although all three problems requiring conceptual understanding had an important aspect in common (the figurative format), in all three the best predictor of success is a different cognitive variable. It was concluded that: (1) the ability to solve computational problems (based on algorithms) is not the major factor in predicting success in solving problems that require conceptual understanding; (2) solving problems based on algorithmic strategies requires formal operational reasoning to a certain degree; and (3) student difficulty in solving problems that require conceptual understanding could be attributed to different cognitive variables.

The Information-processing Demand of Chemistry Problems and Its Relation to Pascual-Leone's Functional M-capacity.

Pascual‐Leone (1972) has conducted task analyses in terms of M‐demand (amount of information processing required by the task) and demonstrated that the phenomenon of ‘horizontal decalages’, described by Piaget, can be accounted for by increasing demands of information processing. It has been shown that formal operational reasoning is required to balance even simple, one‐step chemical equations, while formal reasoning and a sufficiently large M‐capacity are required to balance more complex, multi‐step chemical equations. The objective of the present study is to investigate the relation between functional M‐capacity (Mf) and student performance in solving chemistry problems of increasing M‐demand. It was found that student performance decreased as the M‐demand of the problems increased. Similarly, the correlation coefficients between Mf‐ and student performance increased progressively as the M‐demand of the problems increased.

Promoting conceptual change in first year students’ understanding of evaporation

We constructed the PDEODE (Predict-Discuss-Explain-Observe-Discuss-Explain) teaching strategy, a variant of the classical POE (Predict-Observe-Explain) activity, to promote conceptual change, and investigated its effectiveness on student understanding of the evaporation concept. The sample consisted of 52 first year students in a primary science education department. The students’ ideas were revealed by a test consisting of eight questions. The PDEODE teaching strategy was designed on the basis of the students’ preconceptions. Conceptual change in students’ understanding of evaporation was evaluated by administering the same test as pre-, post and delayed post-test. The test scores were analyzed by both qualitative and quantitative methods. Statistical analysis using general linear model repeated measures of student test scores point to statistically significant differences in pre-, post-, delayed post tests and total scores (p<0.05), suggesting that the strategy helped students to achieve a better conceptual understanding. Further, no statistically significant differences were observed between post-test and delayed post-test scores, suggesting that teaching strategy enabled students to retain their new conceptions in their long-term memory.

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‐Leones M‐capacity (information processing) and Witkins 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 probl...

From "Algorithmic Mode" to "Conceptual Gestalt" in Understanding the Behavior of Gases: An Epistemological Perspective.

Abstract The experimental work of Boyle, Charles and Gay‐Lussac dealt with observable properties of gases, and the Ideal Gas Law is based entirely on empirical evidence (inductive process). According to Hanson a law might have been arrived at empirically (enumerating particulars); it could then be built into a hypothetico‐deductive (H‐D) system as a higher order proposition. From an epistemological perspective, resolution of gas problems based on the Ideal Gas Law, derived by the inductive process, primarily requires manipulation (i.e. enumeration of particulars; of the different variables, and thus can be characterized by the ‘algorithmic mode’. On the other hand, resolution of gas problems based on the Ideal Gas Law, which derives its meaning from the Kinetic‐Molecular Theory of Maxwell‐Boltzmann (an H‐D system), requires the understanding of a pattern within which data appear intelligible, i.e. a sort of ‘conceptual gestalt’. One of the main objectives of this study is to compare performance of student...