Surface Passivation of Mercury-Cadmium-Telluride Infrared Detectors

The theoretical considerations and practical aspects of passivating insulator films, in the context of their use on high-performance mercury cadmium telluride (MCT) infrared detectors are reviewed. The methods of growth, the interface properties and the applications of both native and deposited passivant films have been discussed. Native films include anodic, chemical, photochemical, and plasma oxides as well as anodic sulphides and fluoro-oxides. Deposited films include ZnS, photo-CVD-grown SiO2, CDTe, and SiN/sub x/. The properties of all these passivant films on MCT have been summarized

When the fiction of learning is kept: A case of networking two theoretical views

International audienceA case of networking two didactic phenomena - the Topaze effect and the Funnel communications pattern - through analyses of the same episode from two theoretical perspectives is presented. It shows how this networked analysis deepens insight into the kind of learning of the same episode through complementary views, how it strengthens the theoretical understanding the two phenomena as parts of the theories and how it uncovers blind spots of the theories themselves

Consolidating one novel structure whilst constructing two more

This study reports the cognitive processing of a Year 8 female student (Kerri) during a test, and during her subsequent homework as she consolidated as part of abstracting; a topic of recent research interest. This case adds to the body of knowledge about how constructing and consolidating can occur simultaneously. The analysis captured the complexity of the cognitive processing, and their intertwined nature. Data was captured through lesson video, and post-lesson, video-stimulated reconstructive student interviews. It was found that Kerri&rsquo;s constructing and consolidating included characteristics previously identified by others, and an additional feature. Her constructing included &ldquo;branching&rdquo; (Kidron &amp; Dreyfus, 2004, p. 159); but unlike the case cited, one of these branches related to a new goal.<br /

Understanding irrational numbers by means of their representation as non-repeating decimals

International audienceResearch study on students' conceptions of irrational numbers upon entering university is of importance towards the transition to university. In this paper, we analyze students' conceptions of irrational numbers using their representation as non-repeating infinite decimals. The majority of students in the study identify the set of all decimals (finite and infinite) with the set of rational numbers. In spite of the fact that around 80% of the students claimed that they had learned about irrational numbers, only a small percentage of students (19%) showed awareness of the existence of non-repeating infinite decimals.</p

PRIMARY SCHOOL STUDENTS' ABSTRACTION LEVELS OF WHOLE-HALF-QUARTER CONCEPTS ACCORDING TO RBC THEORY

Whole-half-quarter are important mathematical concepts that form the basis of fractions and should be well understood for advancing mathematical topics. The aim of this study is to determine the primary school students' abstraction levels of whole-half-quarter concepts according to RBC theory. The participants of the study are six students (8 age group) from the second grade of primary school. The data of the research which is a case study were collected through worksheets and semi-structured interviews. The data obtained from interviews were analyzed by qualitative data analysis steps. The abstraction levels of students were evaluated according to RBC theory. As a result of the study, it was seen that many of the students could not abstract the whole, half and quarter concepts. It was determined that difficulties of students to abstract the whole-half-quarter concepts resulted from reasons such as not understanding the half and quarter concepts, not being able to divide the whole into two equal parts, not being able to divide one dimensional shapes into half and quarter, generalizing dividing into quarter as putting a "+", not being able to divide into four equal parts for quarter

Theories in and of Mathematics Education

Mathematics Education; Learning; Teachin

Definir, buscar ejemplos, conjeturar… para probar si un número es feliz

Para formar futuros matemáticos es necesario que realicen a tareas en las que deban actuar como tales. En la tarea descrita en este artículo, un grupo de alumnos deben enfrentarse a una definición nueva para ellos: la del concepto de número feliz; deben extraer información que les permita comprenderla para generar ejemplos que respondan con la definición, poder identificar no ejemplos y encontrar organizadores genéricos para construir espacios de ejemplos y finalmente resolver una situación en la que están implicados estos números. Las interacciones dentro del grupo fueron grabadas y analizadas utilizando el modelo RBC-C (Schwarz, Dreyfus & Hershkowitz, 2009) para documentar cómo tuvo lugar el proceso. Los resultados muestran que, a pesar de algunos errores de los que ellos mismos son conscientes, los alumnos se entusiasmaron con la tarea y consiguieron ir más allá de lo que se les propuso

„Ich zeig‘ uns was, was du nicht siehst“ – Zur epistemischen Rolle von Gesten

Prozesse der Wissenskonstruktion werden bisher vor allem in Bezug auf Sprache und Inskription in sozialen Interaktionen untersucht (z.B. Bikner-Ahsbahs 2005). Jedoch zeigen neue Studien insbesondere bei graphischnahen Lernumgebungen, dass auch der Gebrauch von Gesten einen Beitrag zur Wissenskonstruktion leistet (z.B. Reynolds & Reeves 2002). Im vorliegenden Beitrag wird die Fallstudie einer Masterarbeit vorgestellt. Diese untersucht, welchen Beitrag Gesten zum mathematischen Erkenntnisprozess bei arithmetisch-analytischen und somit graphisch-abstinenten Aufgaben leisten können