The Oil Drop Experiment: How Did Millikan Decide What Was an Appropriate Drop?

The oil drop experiment is considered an important contribution to the understanding of modern physics and chemistry. The objective of this investigation is to study and contrast the views and understanding with respect to the experiment of physicists or philosophers of science with those of authors of physics or chemistry textbooks and laboratory manuals. Results obtained show that physicists and philosophers of science do understand that the experiment is difficult to perform even today, primarily because of the difficulty associated with the selection of the appropriate drops and that consensus was achieved in the scientific community after a bitter dispute between R.A. Millikan and F. Ehrenhaft. In contrast, authors of physics and chemistry textbooks and laboratory manuals ignore the controversy (especially with respect to the selection of the drops) and present an inductivist interpretation in which empirical data were crucial in the quantization of the charge of the electron. By highlighting the difference between the methodologies of Millikan and Ehrenhaft, textbooks can facilitate students' conceptual understanding of the experiment and thus stimulate interest. It is concluded that although experimental data are important, epistemologically their interpretation through conflicts and controversies is even more important.L'on considère que l'expérience de la gouttelette d'huile apporte beaucoup à la physique et la chimie modernes. L'objectif de cette recherche est de comparer les avis et les connaissances des physiciens ou des philosophes des sciences quant à cette expérience à ceux des auteurs de manuels et de cahiers de laboratoire de physique ou de chimie. Les résultats indiquent que les physiciens et les philosophes des sciences comprennent que, même aujourd'hui, l'expérience est difficile à réaliser, principalement à cause de la difficulté de choisir les gouttelettes appropriées, question sur laquelle la communauté scientifique n'est arrivée au consensus qu'après une amère dispute entre R.A. Millikan et F. Ehrenhaft. Par contre, les auteurs de manuels et de cahiers de laboratoire de physique ou de chimie font abstraction de la controverse (surtout en ce qui concerne la sélection des gouttelettes) et présentent une interprétation inductive selon laquelle des données empiriques étaient d'importance cruciale dans la quantification de la charge de l'électron. En faisant ressortir les différences entre les méthodologies de Millikan et Ehrenhaft, les manuels peuvent aider les élèves à conceptualiser l'expérience, stimulant ainsi l'intérêt que ceux-ci portent au domaine. Bien que les données expérimentales soient importantes, on conclut que, sur le plan épistémologique, l'interprétation de celles-ci par le biais des conflits et des controverses est encore plus importante

Response to contradiction: Conflict resolution strategies used by students in solving problems of chemical equilibrium

The main objective of this investigation was to show that a novel problem of chemical equilibrium based on a closely related sequence of items can facilitate students' conceptual understanding. Students were presented a chemical reaction in equilibrium to which a reactant was added as an external effect. A series of three studies were designed. In Study 1, the sequence of items started with a major alternative conception, namely, "After the reaction has started, the rate of the forward reaction increases with time and that of the reverse reaction decreases, until equilibrium is reached." In Study 2, the major alternative conception was presented the last. In Study 3, instead of the sequence, only the following statement was presented: "Rate of the reverse reaction increases gradually." In all three studies students had to agree/disagree with the statements and provide justifications. Results obtained show that at least one group of students, in Study 1 used a contradictory response pattern based on the generation and resolution of a cognitive conflict, which facilitated conceptual understanding. In Studies 2 and 3 students did not experience a similar cognitive conflict. Given the complexity of conceptual change and students' resistance to alter their alternative conceptions (cf. hard core

History and Philosophy of Science as a Guide to Understanding Nature of Science

Nature of science (NOS) is considered to be a controversial topic by historians, philosophers of science and science educators. It is paradoxical that we all teach science and still have difficulties in understanding what science is and how it develops and progresses. A major obstacle in understanding NOS is that science is primarily ‘unnatural’, that is it cannot be learned by a simple observation of phenomena. In most parts of the world history and philosophy of science are ‘inside’ science content and as such can guide our understanding of NOS. However, some science educators consider the ‘historical turn’ as dated and hence neglect the historical approach and instead emphasize the model based naturalist view of science. The objective of this presentation is to show that the historical approach is very much a part of teaching science and actually complements naturalism. Understanding NOS generally requires two aspects of science: Domain general and domain specific. In the classroom this can be illustrated by discussing the atomic models developed in the early 20th century which constitute the domain specific aspect of NOS. This can then lead to an understanding of the tentative nature of science that is a domain general aspect of NOS. A review of the literature in science education reveals three views (among others) of understanding NOS: a) Consensus view: It attempts to include only those domain-general NOS aspects that are the least controversial (Lederman, Abd-El-Khalick); b) Family resemblance view: Based on the ideas of Wittgenstein, this view promotes science as a cognitive system (Irzik, Nola); c) Integrated view: this view postulates that both domain general and domain specific aspects of NOS are not dichotomous but rather need to be integrated and are essential if we want students to understand ‘science in the making’ (Niaz). The following framework helps to facilitate integration: i) Elaboration of a theoretical framework based on presuppositions, guiding assumptions, and previous experience of the scientist; ii) Formulation of research questions; iii) Operationalizing heuristic principles; iv) Designing experiments; and v) Understanding NOS. Various examples from history of science are provided to show how understanding ‘science in the making’ is important in order to integrate domain general and domain specific aspects of NOS. It is concluded that the integrated view of NOS facilitates ‘science in the making’ as based on the postulation of alternative interpretations of experimental data, which are controversial and thus science is primarily a human enterprise.Nature of science (NOS) is considered to be a controversial topic by historians, philosophers of science and science educators. It is paradoxical that we all teach science and still have difficulties in understanding what science is and how it develops and progresses. A major obstacle in understanding NOS is that science is primarily ‘unnatural’, that is it cannot be learned by a simple observation of phenomena. In most parts of the world history and philosophy of science are ‘inside’ science content and as such can guide our understanding of NOS. However, some science educators consider the ‘historical turn’ as dated and hence neglect the historical approach and instead emphasize the model based naturalist view of science. The objective of this presentation is to show that the historical approach is very much a part of teaching science and actually complements naturalism. Understanding NOS generally requires two aspects of science: Domain general and domain specific. In the classroom this can be illustrated by discussing the atomic models developed in the early 20th century which constitute the domain specific aspect of NOS. This can then lead to an understanding of the tentative nature of science that is a domain general aspect of NOS. A review of the literature in science education reveals three views (among others) of understanding NOS: a) Consensus view: It attempts to include only those domain-general NOS aspects that are the least controversial (Lederman, Abd-El-Khalick); b) Family resemblance view: Based on the ideas of Wittgenstein, this view promotes science as a cognitive system (Irzik, Nola); c) Integrated view: this view postulates that both domain general and domain specific aspects of NOS are not dichotomous but rather need to be integrated and are essential if we want students to understand ‘science in the making’ (Niaz). The following framework helps to facilitate integration: i) Elaboration of a theoretical framework based on presuppositions, guiding assumptions,  and previous experience of the scientist; ii) Formulation of research questions; iii) Operationalizing heuristic principles; iv) Designing experiments; and v) Understanding NOS. Various examples from history of science are provided to show how understanding ‘science in the making’ is important in order to integrate domain general and domain specific aspects of NOS. It is concluded that the integrated view of NOS facilitates ‘science in the making’ as based on the postulation of alternative interpretations of experimental data, which are controversial and thus science is primarily a human enterprise.Historia y Filosofía de la Ciencia como una guía para entender la naturaleza de la CienciaLa naturaleza de la ciencia (NOS) se considera que es un tema controvertido por los historiadores, los filósofos de educadores de la ciencia y de la ciencia. Es paradójico que todos enseñar ciencia y todavía tienen dificultades para comprender lo que es la ciencia y cómo se desarrolla y progresa. Un obstáculo importante en la comprensión de la NOS es que la ciencia es sobre todo "antinatural", es decir que no se puede aprender mediante una simple observación de los fenómenos. En la mayor parte de la historia del mundo y la filosofía de la ciencia son contenido de la ciencia "dentro" y como tal puede guiar nuestra comprensión de la NOS. Sin embargo, algunos profesores de disciplinas científicas consideran el "giro histórico" como anticuada y, por tanto, el abandono del enfoque histórico y en su lugar hacen hincapié en el modelo basado en la visión naturalista de la ciencia. El objetivo de esta presentación es mostrar que el enfoque histórico es una parte muy importante de la enseñanza de la ciencia y de hecho complementa el naturalismo. La comprensión de la NOS requiere generalmente dos aspectos de la ciencia: dominio general y dominio específico. En el aula esto puede ser ilustrado por la discusión de los modelos atómicos desarrollados en el siglo 20 que constituyen el aspecto específico de dominio de la NOS. Esto puede conducir a una comprensión de la naturaleza provisional de la ciencia que es un aspecto general de dominio de la NOS. Una revisión de la literatura en la educación científica revela tres puntos de vista (entre otros) de entendimiento NOS: a) Vista Consenso: Se intenta incluir sólo aquellos aspectos NOS dominio general que son los menos controvertido (Lederman, Abd-El-Khalick); b) Vista aire de familia: Sobre la base de las ideas de Wittgenstein, este punto de vista promueve la ciencia como un sistema cognitivo (Irzik, Nola); c) Visión integrada: este punto de vista postula que tanto el dominio de dominio general y aspectos específicos de la NOS no son dicotómicas, sino más bien deben ser integrados y son esenciales si queremos que los estudiantes entienden 'la ciencia en la toma' (Niaz). El siguiente marco ayuda a facilitar la integración: i) Elaboración de un marco teórico basado en presuposiciones, los supuestos de guía, y la experiencia previa del científico; ii) La formulación de preguntas de investigación; iii) Operacionalización de principios heurísticos; iv) El diseño de experimentos; y v) la comprensión de NOS. Varios ejemplos de la historia de la ciencia se proporcionan para mostrar cómo la comprensión 'la ciencia en la toma' es importante con el fin de integrar dominio generales y de dominio de aspectos específicos de la NOS. Se concluye que la visión integrada de la NOS facilita 'la ciencia en la toma "como basado en la postulación de interpretaciones alternativas de los datos experimentales, que son controvertidos y por lo tanto la ciencia es ante todo una empresa humana.História e Filosofia da Ciência como um guia para a compreensão da natureza da CiênciaNatureza da ciência (NOS) é considerado como sendo um tema controverso por historiadores, filósofos de educadores de ciências e ciências. É paradoxal que todos nós ensinar ciência e ainda têm dificuldade em compreender o que é ciência e como ela se desenvolve e progride. Um grande obstáculo na compreensão NOS é que a ciência é essencialmente "não natural", isto é, não pode ser aprendido através da simples observação dos fenômenos. Na maior parte da história do mundo e filosofia da ciência se contentam ciência "dentro" e, como tal, pode guiar nossa compreensão da NOS. No entanto, alguns educadores de ciências consideram a "virada histórica", como antiquado e, portanto, negligenciar a abordagem histórica e em vez disso enfatizar o modelo baseado visão naturalista da ciência. O objetivo desta apresentação é mostrar que a abordagem histórica é uma parte muito importante de ensinar a ciência e, na verdade, complementa naturalismo. Compreender NOS geralmente requer dois aspectos da ciência: específico geral e de domínio Domínio. Na sala de aula o que pode ser ilustrado por discutir os modelos atômicos desenvolvidos no início do século 20 que constituem o aspecto específico de domínio de NOS. Este pode, então, levar a uma compreensão da natureza experimental da ciência que é um aspecto geral de NOS domínio. Uma revisão da literatura na educação científica revela três pontos de vista (entre outros) de entendimento NOS: a) visão de consenso: Ele tenta incluir apenas os aspectos NOS domínio geral que são o menos controverso (Lederman, Abd-El-Khalick); b) vista semelhança de família: Com base nas ideias de Wittgenstein, essa visão promove a ciência como um sistema cognitivo (Irzik, Nola); c) Visão integrada: esta visão postula que tanto domínio gerais e domínio aspectos específicos da NOS não são dicotômica mas precisam ser integradas e são essenciais se queremos que os alunos a compreender a "ciência na tomada '(Niaz). O quadro a seguir ajuda a facilitar a integração: i) Elaboração de um quadro teórico baseado em pressupostos, guiando pressupostos e experiência anterior do cientista; ii) Formulação de questões de pesquisa; iii) princípios heurísticos Operacionalização; iv) Projetando experimentos; e v) Entendimento NOS. Vários exemplos da história da ciência são fornecidos para mostrar como o entendimento "ciência na tomada 'é importante, a fim de integrar os aspectos específicos da NOS domínio geral e de domínio. Conclui-se que a visão integrada da NOS facilita a "ciência na tomada de decisões", como base na postulação de interpretações alternativas de dados experimentais, que são controversos e, portanto, a ciência é essencialmente um empreendimento humano

Formación de Profesores de Ciencias: Una Perspectiva basada en la Historia y Filosofía de la Ciencia

El objetivo de este artículo es de reseñar algunos de los experimentos más importantes de los últimos cien años, dentro de una perspectiva crítica de la historia y filosofía de la ciencia. El análisis de los experimentos muestra que el desarrollo científico es muy complejo e involucra interpretaciones alternativas de los datos experimentales, lo que inevitablemente produce conflictos y controversias entre los científicos. Muchos de estos conflictos requieren la intervención de la comunidad científica para su resolución y a veces tardan largos periodos de tiempo. Una revisión bibliográfica de la enseñanza de la ciencia muestra que la mayoría de las/los profesoras(es) de ciencia y textos ignoran estos aspectos del desarrollo científico. Se sugiere que la inclusión de una perspectiva basada en la historia y filosofía de la ciencia puede facilitar una mejor comprensión de la ciencia y asimismo motivar a los estudiantes y los profesores de ciencia, para seguir haciendo la ciencia

El experimento de Rutherford en el contexto de la Historia y Filosofía de la Ciencia y sus implicaciones para los textos de Física

This article has evaluated the presentation of Rutherford's experiment in 35 university level general physics textbooks, within a History and Philosophy of Science context. In general the textbooks ignore the importance of rivalry between two conflicting frameworks, as for example Thomson and Rutherford models of the atom (criterion 1). Very few textbooks mention that the crucial argument in favor of the Rutherford model was not the large angle of deflection of alpha particles but rather the finding that only 1 in 20.000 particles deflected through large angles (criterion 2). Again, the textbooks ignore the controversy with respect to Thomson's hypothesis of compound scattering in contrapositlon to Rutherford's hypothesis of single scattering, in order to explain the large angle deflections of alpha particles (criterion 3). Very few textbooks present the work ofThomson and Rutherford in ahistorical context and lack a History and Philosophy of Science perspective

Chronic inflammatory demyelinating polyneuropathy as a paraneoplastic manifestation of colorectal carcinoma: What do we know?

The pathogenesis of chronic inflammatory demyelinating polyneuropathy (CIDP) remains highly debated among experts. In recent times, literature has divulged a riveting yet plausible association between colorectal carcinoma and CIDP as its paraneoplastic ramification. Initially, research suggested that chronic inflammatory demyelinating polyneuropathy (CIDP) was caused solely by macrophages. However, recent studies have insinuated towards an alternative pathogenesis, one involving autoantibodies against paranodal junction proteins. These two distinct mechanisms are the primary contenders responsible for the development of CIDP, rendering it an elusive paraneoplastic manifestation of colorectal carcinoma.</p

Constructivism: Defense or a Continual Critical Appraisal – A Response to Gil-Pérez et al.

Abstract. This commentary is a critical appraisal of Gil-Pérez et al.’s (2002) conceptualization of constructivism. It is argued that the following aspects of their presentation are problematic: (a) Although the role of controversy is recognized, the authors implicitly subscribe to a Kuhnian perspective of ‘normal’ science; (b) Authors fail to recognize the importance of von Glasersfeld’s contribution to the understanding of constructivism in science education; (c) The fact that it is not possible to implement a constructivist pedagogy without a constructivist epistemology has been ignored; and (d) Failure to recognize that the metaphor of the ‘student as a developing scientist’ facilitates teaching strategies as students are confronted with alternative/rival/conflicting ideas. Finally, we have shown that constructivism in science education is going through a process of continual critical appraisals

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified