La enseñanza de ciencias basada en la elaboración de modelos

Se discute una propuesta para planificar la enseñanza de ciencias y la puesta en práctica de actividades, orientada a disminuir el énfasis que se ha venido haciendo en la transmisión de conocimientos. En nuestra propuesta se trata de poner a los alumnos en disposición de comprender los modelos científicos (así como la naturaleza de la ciencia y sus formas de pensamiento asociados) y a la vez ser capaces de manejar con sentido crítico situaciones relacionadas con las ciencias. Esta propuesta surge de la constatación de que para elaborar estrategias de enseñanza se necesita tomar en consideración a la vez aspectos de diferente naturaleza, así como un modelo cognitivo de la ciencia que se fundamente en la construcción de modelos (Izquierdo y Adúriz-Bravo, 2003).The need for teaching strategies elaborated by taking into account several different nature features as well as a cognitive model of science (Izquierdo y Adúriz-Bravo, 2003) based on the construction of models is presented. From them, a proposal is discussed for planning science teaching and conducting teaching activities that aim at changing the emphasis in science education from the transmission of existing knowledge to situations in which students will really understand the models of science (as well as the nature of science and the scientific reasoning) and be able to critically deal with science-related situations

Contribucions de la investigació didàctica a l'ensenyament de la química basat en la modelització

Un dels grans reptes dels educadors químics del segle XXI deriva d'una qüestió àmplia: com es pot aconseguir que l'ensenyament de la química es torni més autèntic? Amb la finalitat de discutir alguns aspectes relatius a aquesta qüestió, es presenten algunes reflexions provinents de l'àrea de l'ensenyament de la química que són motiu d'atenció entre els investigadors, simultàniament amb l'aprenentatge del contingut químic i amb el desenvolupament de certes capacitats dels estudiants relacionades amb el fet de pensar des del punt de vista químic i d'expressar i discutir idees amb l'objectiu de construir el coneixement dels estudiants. Aquestes investigacions van ser realitzades a classe, en un context d'ensenyament fonamentat en la modelització.In the 21st century, one of the great challenges faced by chemistry educators arises from a comprehensive question: how can chemistry teaching become more authentic? Some thoughts about research in chemistry education are presented in this article. It became clear that many researchers were worried about students learning about the concepts of chemistry, about understanding from a chemistry viewpoint, and about helping students to construct knowledge. These investigations were conducted in normal classrooms in model-based teaching contexts

Eliminating Direct Ground Combat Definition and Assignment Rule: Internal Preparations for Implementation

Decades before the elimination of gender restrictions in the U.S. military, ground combat was an equal opportunity issue for women. Direct combat units, such as infantry and artillery, are now open to female enlistment. The purpose of this study was to examine the efforts, challenges and/or successes, of incorporating women into a U.S. Army combat brigade in a single state. The frame-critical approach was used to outline the competing arguments between supporters and opponents of women in combat. The research questions guiding the study included how gender integration is perceived with regards to strength and survivability of the unit, and how future conflict will govern decisions about sending women into combat. A qualitative case study was employed with semi structured interviews with commanders of the combat brigade, given their proximity to the issue and responsibility in the implementation process. The selected brigade was serving as the initial test bed of evaluation for the rest of the state\u27s combat units. The data collected via the interviews were cross-checked with documentary data including declassified memorandums, technical reports, and execution orders. During the analysis phase, the data were organized and coded to identify themes related to the experiences of the command structure. Overall, the officers were supportive of the policy mandate and expressed viewpoints that validated both oppositional and advocacy arguments. The implications for social change include how the military is working to validate performance standards to positively influence policy on gender integration, and the combat brigade utilized in this study is an example for the rest of the United States as it is slated to have the most female recruits for combat positions than any other state beginning in 2017

Studies of the Crystallization Process of Aluminum-Silicon Alloys Using a High Temperature Microscope

It is shown that primary silicon crystals grow polyhedral in super-eutectic AlSi melts and that phosphorus additives to the melt confirm the strong seeding capacity. Primary silicon exhibits strong dendritic seeding effects in eutectic silicon phases of various silicon alloys, whereas primary aluminum does not possess this capacity. Sodium addition also produces a dendritic silicon network growth in the interior of the sample that is attributed to the slower silicon diffusion velocity during cooling

Analogies in high school Brazilian chemistry textbooks

This paper presents and discusses an analysis of the analogies presented by Brazilian chemistry textbooks for the medium level. The main aim of the analysis is to discuss whether such analogies can be said good teaching models. From the results, some aspects concerning with teachers' role are discussed. Finally, some new research questions are emphasised

Metacognição em modelagem desenvolvendo conhecimentos sobre Ciência

Este trabalho apresenta uma análise da contribuição de atividades de modelagem para o desenvolvimento do metaconhecimento dos alunos, com foco nas relações que eles estabelecem entre as atividades de modelagem desenvolvidas por eles e o processo de construção do conhecimento científico. Foram realizadas entrevistas com 12 alunos (15-16 anos) cujo ensino de química foi baseado em atividades de modelagem ao longo de todo o ano letivo. As questões visavam favorecer aos alunos explicitar os caminhos percorridos para a elaboração de seus modelos e comparar esse processo àquele vivido pelos cientistas. A promoção de uma reflexão comparativa entre os dois contextos levou ao conhecimento sobre o próprio processo de modelagem e, ainda, sobre a natureza da ciência, o que contribuiu para desmistificá-la sob certos aspectos

Usando analogias com função criativa: uma nova estratégia para o ensino de química

En aquest article es relata una experiencia d'aula amb alumnes de 15-16 anys, als quals es va demanar que creessin analogies per explicar la formació d'un enllaç químic i que les valoressin, considerant-ne tots els aspectes positius i negatius. En analitzar les respostes dels alumnes, la professora se'n va adonar d'algunes dificultats en la comprensió d'aspectes rellevants sobre l'enllaç químic, que no havien estat identificades anteriorment. Llavors, va poder modificar l'ensenyament, intentant discutir els aspectes centrals d'aquestes dificultats dels alumnes.In this paper, we present a teaching experience conducted with 15-16 years-old students. They were asked to produce analogies to explain the formation of a chemical bond and to criticise them from the consideration of their positive and negative parts. By analysing the students’ answers, the teacher realised some of their difficulties in understanding chemical bonds that had not been identified before. Therefore, she could change the teaching in an attempt to discuss the central aspects of the students’ difficulties