Constructivism’s New Clothes: The Trivial, the Contingent, and a Progressive Research Programme into the Learning of Science

Constructivism has been a key referent for research into the learning of science for several decades. There is little doubt that the research into learners’ ideas in science stimulated by the constructivist movement has been voluminous, and a great deal is now known about the way various science topics may commonly be understood by learners of various ages. Despite this significant research effort, there have been serious criticisms of this area of work: in terms of its philosophical underpinning, the validity of its most popular constructs, the limited scope of its focus, and its practical value to science teaching. This paper frames this area of work as a Lakatosian Research Programme (RP), and explores the major criticisms of constructivism from that perspective. It is argued that much of the criticism may be considered as part of the legitimate academic debate expected within any active RP, i.e. arguments about the auxiliary theory making up the ‘protective belt’ of the programme. It is suggested that a shifting focus from constructivism to ‘contingency in learning’ will allow the RP to draw upon a more diverse range of perspectives, each consistent with the existing hard core of the programme, which will provide potentially fruitful directions for future work and ensure the continuity of a progressive RP into learning science.     

The Views and Influence of Ernst Von Glasersfeld: An Introduction

Research into learners' ideas about science suggests that students often have alternative conceptions about important science concepts. Because of this dissatisfaction, constructivism has been adopted as a theoretical framework by many teachers and researchers, and it has had a curricular influence in many countries. Constructivism is much more than an educational doctrine and we are aware that a ‘science war’ about the possibility of objectivity is in progress. ‘Constructivism’ cannot necessary be a package deal: it must be possible to accept educational suggestions deemed useful without buying all the epistemology or the metaphysical implications. The claim that cognitive agents understand the world by constructing mental representations of it can be a shared suggestion for changing science instruction. Many teachers are much more concerned in finding productive teaching methods than about philosophical questions as if knowledge must be considered an objective representation of the real world or not. We have to ponder if some ideas from the constructivist theory of instruction can help instructors to become better teachers. The pragmatic suggestions that come from the constructivist theory of instruction developed by von Glasersfeld, the leading proponent of radical constructivism, could be a good start in this␣search.     

The production of purity as the production of knowledge

Using the concept of purity to reflect on the relationship between chemical practice and the philosophy of science, this article considers the philosophical significance of the chemical manipulations that aim to purify or otherwise transform matter. Starting from a consideration of the nature and role of pure (or idealised) examples in philosophy of science, the article underlines the temptation towards abstraction and theory for both scientists and philosophers. The article goes on to argue that chemistry, despite its increasing theoretical sophistication, is a science that remains particularly close to laboratory manipulations. This point is made in reference to the work of Gaston Bachelard on the production of purity and with the aid of historical examples, notably exploring the interplay between techniques of purification and the definition of elements, with special attention paid to Lavoisier’s definition of elements as the final limit of analysis. The closing section concerns the manufacture of steel from iron ore in the eighteenth century, illustrating this process using texts by Pierre-Joseph Macquer and Denis Diderot. Steel production is used to illustrate the kinds of philosophical question that are raised by paying attention to the details of chemical practice rather than jumping straight to chemical theory and also suggests how scientific theory can emerge from this practice itself.     

Histoires de fontes. Entre le phlogistique et la plombagine : où situer la « fonte à l'oxygène » ?

Iron stories. Between phlogiston and plumbago : which place for ‘oxygen cast-iron’ ? The evolution of knowledge on steel and iron, with the first quantitative chemical analysis by Lavoisier, is described along the 18th century and the first years of the 19th. After the classification by Réaumur of wrought iron, steel and cast iron, based on an increasing content of ‘sulphurs and salts’, replaced by phlogiston and plumbago, the publication by Lavoisier of a high oxygen content in cast iron darkened the understanding of iron metallurgy. It was necessary to wait until the beginning of the 19th century, when Berzelius restored the situation.     

Breaking the law: promoting domain-specificity in chemical education in the context of arguing about the periodic law

In this paper, domain-specificity is presented as an understudied problem in chemical education. This argument is unpacked by drawing from two bodies of literature: learning of science and epistemology of science, both themes that have cognitive as well as philosophical undertones. The wider context is students’ engagement in scientific inquiry, an important goal for science education and one that has not been well executed in everyday classrooms. The focus on science learning illustrates the role of domain specificity in scientific reasoning. The discussion on epistemology of science presents ideas from the emerging field of philosophy of chemistry to highlight the much neglected area of epistemology in chemical education. Domain-specificity is exemplified in the context of chemical laws, in particular the Periodic Law. The applications of the discussion for chemical education are explored in relation to argumentation, itself an epistemologically grounded discourse pattern in science. The overall implications include the need for reconceptualization of the nature of teaching and learning in chemistry to include more particular epistemological aspects of chemistry.     

Recommended Questions on the Road towards a Scientific Explanation of the Periodic System of Chemical Elements with the Help of the Concepts of Quantum Physics

Periodic tables (PTs) are the ‘ultimate paper tools’ of general and inorganic chemistry. There are three fields of open questions concerning the relation between PTs and physics: (i) the relation between the chemical facts and the concept of a periodic system (PS) of chemical elements (CEs) as represented by PTs; (ii) the internal structure of the PS; (iii)␣The relation between the PS and atomistic quantum chemistry. The main open questions refer to (i). The fuzziness of the concepts of chemical properties and of chemical similarities of the CE and their compounds guarantees the autonomy of chemistry. We distinguish between CEs, Elemental Stuffs and Elemental Atoms. We comment on the basic properties of the basic elements. Concerning (ii), two sharp physical numbers (nuclear charge and number of valence electrons) and two coarse fuzzy ranges (ranges of energies and of spatial extensions of the atomic orbitals, AOs) characterize the atoms of the CEs and determine the two-dimensional structure of the PS. Concerning (iii), some relevant ‘facts’ about and from quantum chemistry are reviewed and compared with common ‘textbook facts’. What counts in chemistry is the whole set of nondiffuse orbitals in low-energy average configurations of chemically bonded atoms. Decisive for the periodicity are the energy gaps between the core and valence shells. Diffuse Rydberg orbitals and minute spin–orbit splittings are important in spectroscopy and for philosophers, but less so in chemical science and for the PS.     

Another scientific practice separating chemistry from physics: thought experiments

Thought experiments in the history of science display a striking asymmetry between chemistry and physics, namely that chemistry seems to lack well-known examples, whereas physics presents many famous examples. This asymmetry, I argue, is not independent data concerning the chemistry/physics distinction. The laws of chemistry such as the periodic table are incurably special, in that they make testable predictions only for a very restricted range of physical conditions in the universe which are necessarily conditioned by the contingences of chemical investigation. The argument depends on how ‚thought experiment’ is construed. Here, several recent accounts of thought experiments are surveyed to help formulate what I call ‚crucial’ thought experiments. These have a historical role in helping to judge between hypotheses in physics, but are not helpful in chemistry past or present.     

Elements, Principles and the Narrative of Affinity

In the 18th century, the concept of ‘affinity’, ‘principle’ and ‘element’ dominated chemical discourse, both inside and outside the laboratory. Although much work has been done on these terms and the methodological commitments which guided their usage, most studies over the past two centuries have concentrated on their application as relevant to Lavoisier's oxygen theory and the new nomenclature. Kim's affinity challenges this historiographical trajectory by looking at several French chemists in the light of their private thoughts, public disputations and communal networks. In doing so, she tells a complex story which points to the methodological and practical importance of industrial and medical chemistry. The following review highlights the advantages and snares of such an approach and makes a few historiographical points along the way. This revised version was published online in August 2006 with corrections to the Cover Date.     

The Si-doped planar tetracoordinate carbon (ptC) unit CAl<Subscript>3</Subscript>Si<Superscript>−</Superscript> could be used as a building block or inorganic ligand during cluster-assembly

Currently, the molecular assembly and growth from a small building block to the bulk compounds have become a focus in various fields. Ever being chemical curiosities, the “anti-van’t Hoff/Le Bel” realm that is associated with tetracoordinate or hypercoordiate planar centers has made vast progress. Being important in the fundamental research areas, the ptC species have potential applications in materials science. The existence of ptC in a divanadium complex and a large number of organometallic compounds have since been reported to possess ptC and these provide us with great hope that many more compounds with ptC building blocks may be synthesized in future. Herein, we report the assembly and stabilization of CAl₃Si⁻ in both the “homo-decked sandwich” and “hetero-decked sandwich” schemes at the B3LYP/6-311+G(d) level. We show that while the Si-doped indeed introduces much complexity during assembly, the electronic and structural integrity feature of CAl₃Si⁻ is well conserved during cluster-assembly, characteristic of a “superatom”. This study should be helpful in understanding the hetero-doped assembly mechanism of the ptC chemistry. Moreover, the present results are expected to enrich the flat carbon chemistry, superatom chemistry, metallocenes and combinational chemistry. Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

On the non-existence of parallel universes in chemistry

This treatise presents thoughts on the divide that exists in chemistry between those who seek their understanding within a universe wherein the laws of physics apply and those who prefer alternative universes wherein the laws are suspended or ‘bent’ to suit preconceived ideas. The former approach is embodied in the quantum theory of atoms in molecules (QTAIM), a theory based upon the properties of a system’s observable distribution of charge. Science is experimental observation followed by appeal to theory that, upon occasion, leads to new experiments. This is the path that led to the development of the molecular structure hypothesis—that a molecule is a collection atoms with characteristic properties linked by a network of bonds that impart a structure—a concept forged in the crucible of nineteenth century experimental chemistry. One hundred and fifty years of experimental chemistry underlie the realization that the properties of some total system are the sum of its atomic contributions. The concept of a functional group, consisting of a single atom or a linked set of atoms, with characteristic additive properties forms the cornerstone of chemical thinking of both molecules and crystals and Dalton’s atomic hypothesis has emerged as the operational theory of chemistry. We recognize the presence of a functional group in a given system and predict its effect upon the static, reactive and spectroscopic properties of the system in terms of the characteristic properties assigned to that group. QTAM gives physical substance to the concept of a functional group.     

Properties and performance of BaxSr1−xCo0.8Fe0.2O3−δ materials for oxygen transport membranes

The present paper discusses the oxygen transport properties, oxygen stoichiometry, phase stability, and chemical and mechanical stability of the perovskites (BSCF) and (SCF) for air separation applications. The low oxygen conductive brownmillerite phase in SCF is characterized using in-situ neutron diffraction, thermographic analysis and temperature programmed desorption but this phase is not present for BSCF under the conditions studied. Although both materials show oxygen fluxes well above 10 ml/cm²·min at T=1,273 K and pO₂=1 bar for self-supporting, 200 μm-thick membranes, BSCF is preferred as a membrane material due to its phase stability. However, BSCF’s long-term stable performance remains to be confirmed. The deviation from ideal oxygen stoichiometry for both materials is high: δ>0.6. The thermal expansion coefficients of BSCF and SCF are 24×10⁻⁶ and 30×10⁻⁶ K⁻¹, respectively, as determined from neutron diffraction data. The phenomenon of kinetic demixing has been observed at pO₂<10⁻⁵ bar, resulting in roughening of the surface and enrichment with alkaline earth metals. Stress–strain curves were determined and indicated creep behavior that induces undesired ductility at T=1,073 K for SCF. Remedies for mechanical and chemical instabilities are discussed.     

The philosophical significance of Mendeleev’s successful predictions of the properties of gallium and scandium

The philosophical significance of Dmitri Mendeleev’s successful predictions of the properties of gallium and scandium vis a vis the acceptance of the Periodic Table 1874–1886 has been debated recently. This author presents evidence that De Boisbaudran and Cleve both respectively predicted the possible existence of gallium and scandium, but on the basis of the old TRIAD methodology. This suggests that these successful Mendeleev predictions were therefore not independent corroboration of the concept of the Periodic System. Instead the significantly independent predictive successes for Mendeleev’s system were (a) the determination of the atomic weight of the known element uranium as 240 instead of the previously accepted 120 in 1874 and (b) the isolation of germanium by Winkler in 1886.     

Highly resistive intergranular phases in solid electrolytes: an overview

Abstract  

The siliceous intergranular phase in acceptor-doped zirconia and ceria and its effect on the ionic conduction across the grain boundaries were reviewed. Not only the abundant siliceous intergranular liquid phase, but also the monolayer-level siliceous intergranular segregation significantly deteriorates the grain-boundary conduction. To decrease the harmful effect of the resistive siliceous phase at the grain boundary, ‘additive scavenging’ or ‘precursor scavenging’ can be employed. The former involves the addition of a secondary phase or another acceptor material with a very high chemical affinity for the siliceous phase, while the latter involves the intergranular phase changing from having a continuous (blocking) configuration to having a discrete (non-blocking) configuration. The mechanisms of various scavenging reactions have been explained, compared, and discussed.     

Elements of the third kind and the spin-dependent chemical force

A lively philosophical debate has lately arisen over the nature of elementhood in chemistry. Two different senses in which the technical term ELEMENT is currently in use by chemists have been identified, leaving chemistry open to the logical fallacy of equivocation. This paper introduces a third, more elemental candidate: the high-enthalpy short-lived unbonded atom. An enthalpy index based on free-atoms-as-elements is established, whereby one can monitor the degree to which an atom’s spin-based attractive force is implemented exo-enthalpically when the atom binds chemically to others. Enthalpy indexing shows that the strength of an atom’s attractive force is proportional to its spin angular momentum. Vibrational spectroscopy shows that the force varies inversely as the fourth power of the inter-atom distance. Both features differentiate the chemical force from the stronger electromagnetic force and from the weaker Van der Waals force.     

Material ejection and redeposition following atmospheric pressure near-field laser ablation on molecular solids

Near-field laser ablation (NF-LA) coupled with mass spectrometry (MS) is very promising for highly spatially resolved chemical analyses on various substrates at atmospheric pressure, for example, in materials and life science applications. Although nanoscale sample craters can be produced routinely, no molecular mass spectra of ablated material from craters of ≤1 μm diameter have ever been acquired by NF-LA MS at atmospheric pressure. Some of the pressing questions are thus how much of the ablated material is transported into the mass spectrometer and in what form. Therefore, material redeposition on the near-field tip’s surface from laser ablation of molecular solids was characterized with scanning electron microscopy. The crater profiles were studied by scanning probe microscopy. The results shown in this study demonstrate that there could be as much as 70% of the ablated material deposited on the near-field tip’s surface. The redeposited products were found to be confined to a height of ~50 μm, thus suggesting that most components inside near-field ablation plumes propagate about the same distance for both anthracene and tris(8-hydroxyquinolinato)aluminum. Nanoparticles ablated from craters of ≤1 μm diameter are clearly observed. Furthermore, observation of tips after ablation of an anthracene surface angled at 60° with respect to a horizontal surface shows that the direction of the near-field ablation plume is neither in the direction of the surface normal nor towards the axis of incident laser beam but deflected further away from surface normal.      

Thermoanalytical Study of the Composition of β-tungsten

The aim of the present work was to provide arguments to the almost ‘hystorical’ problem of what β-tungsten is. WO₃was reduced in dry H₂gas atmosphere in order to examine, whether β-tungsten formed in such a way contains oxygen as part of the lattice described as W_xO (e.g. W₂₀O) or is a pure metallic phase of tungsten. As a result of thermoanalytical measurements and of chemical analysis for oxygen, the assumption is supported that in the 600-800°C temperature range of metal formation not the W_xO (β-W)→W(α-W) transformation but the β-W→α-W structural rearrangement of materials with identical chemical composition is the most probable process. The earlier opinion that the formation of the β-W structure requires the presence of oxygen atoms was not verified by our results. This revised version was published online in July 2006 with corrections to the Cover Date.     

Lavoisier's Achievement; More Than a Chemical Revolution

Abstract

The Chemical Revolution of the late eighteenth century consisted essentially of combustion being explained by the addition of oxygen rather than by the removal of phlogiston. This has been seen as the “paradigm shift” of a scientific revolution in the familiar Kuhnian sense. Yet Lavoisier helped to change chemistry in several other ways as well, particularly by the introduction of a new chemical language. This reorganisation of chemistry, at a time when it was being swamped with many new substances, has great similarity to the slightly earlier systematisation of botany by Linnaeus through the introduction of a binomial nomenclature. A further parallel in the late eighteenth century was the introduction of the metric system, which also introduced a new language. Yet, however one understands the Chemical Revolution, Lavoisier clearly made an enormous difference, not only to the internal science of chemistry, but also to its status. By the end of the 1700s, chemistry had become something of a model science.     

Richard Kirwan's Phlogiston Theory: Its Success and Fate

Abstract

First proposed in the early 1780s, Richard Kirwan's phlogiston theory was the most successful enunciation of the English pneumatic approach to phlogiston. Phlogiston was identified with a material substance, inflammable air. In this paper, I explore the nature of Kirwan's theory, its success in the mid-1780s, the unprecedented collective attack on Kirwan's Essay on Phlogiston by Lavoisier and his colleagues, and Kinvan's ultimate abandonment of phlogistic explanation.     

Regioselective dehydration of axial and equatorial tertiary alcohols with α-methyl group in the cyclohexane ring by Swern’s reagent

Swern’s reagent (a complex of oxalyl chloride with DMSO) was shown to dehydrate tertiary alcohols containing an α-methyl group in the cyclohexane ring. Dehydration of equatorial alcohols affords mixtures of isomeric compounds where isomers with an exocyclic double bond dominate, whereas isomers with an endocyclic double bond prevail in the products of dehydration of axial tertiary alcohols. Thus, Swern’s reagent can serve as a chemical test to determine the configuration of tertiary alcohols containing an α-methyl group in cyclohexane ring. The composition of the products of dehydration of these alcohols with Swern’s reagent is similar to that obtained by their dehydration with POCl₃ in pyridine. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 800–803, April, 1997.