Quelques résultats relatifs aux connaissances disciplinaires de professeurs stagiaires dans des situations simulées d’évaluation de productions d’élèves en mathématiques

Dans cet article, nous étudions l’activité de dix-huit enseignants stagiaires – professeurs des écoles et professeurs de mathématiques – accomplissant des tâches d’évaluation de productions d’élèves en mathématiques. La recherche s’inscrit dans une double orientation didactique : didactique professionnelle et didactique des mathématiques. Le dispositif de recherche, organisé autour d’un « simulateur », permet de ménager des conditions expérimentales analogues pour tous les professeurs. L’identification et la catégorisation des connaissances mobilisées par les enseignants lors de l’accomplissement des tâches d’évaluation servent d’appui à une analyse comparative de leur activité. Les résultats obtenus montrent que les connaissances disciplinaires jouent un rôle essentiel dans la réalisation des tâches que nous leur proposons.This article examines how students’ productions in mathematics are evaluated by eighteen student teachers/practicum, both schoolteachers and math teachers. There are two pedagogical objectives: professional didactics and mathematical didactics. The research design, organized around a “simulator”, allows the authors to arrange analogous experimental conditions for all subjects. The identification and categorization of knowledge that is used by the teachers during their evaluations is then used to support a comparative analysis of their activity. The results show that disciplinary knowledge plays an essential role in the accomplishment of the tasks proposed.En el presente artículo, estudiamos la actividad de diez y ocho docentes en práctica – maestros de las escuelas y maestros de matemáticas – llevando a cabo tareas de evaluación de producciones de alumnos en matemáticas. La investigación se inscribe en una doble orientación didáctica: didáctica profesional y didáctica de las matemáticas. El dispositivo de investigación, organizado alrededor de un «simulador», posibilita la habilitación de condiciones experimentales análogas para todos los maestros. La identificación y la categorización de los conocimientos movilizados por los docentes al momento de cumplir con tareas de evaluación sirven de apoyo a un análisis comparativo de su actividad. Los resultados conseguidos muestran que los conocimientos disciplinarios juegan un papel esencial en la realización de las tareas que les proponemos

Évaluation de la lecture au CP : mise en œuvre d’une approche multiple

Dans cet article, nous présentons un dispositif d’évaluation de la lecture en fin de CP (cours préparatoire) dont l’élaboration repose sur la prise en compte de deux dimensions du savoir-lire, le décodage-identification et la compréhension. Nous analysons la validité des épreuves qui le composent en référence à des modèles du décodage et de l’identification de mots ainsi que de la compréhension de texte. Le dispositif est testé, en passation individuelle, auprès de soixante-huit élèves de CP. Nous montrons par des analyses quantitatives et qualitatives des données l'intérêt d’une approche combinant plusieurs épreuves, dont deux consacrées à la compréhension autonome d'un texte écrit, pour évaluer en lecture des élèves et pour identifier différents types d’élèves en difficulté.In this paper we present an evaluation method to assess the level of reading of end of first-grade children (cours préparatoire), which takes into account two reading skills dimensions: decoding-identifying and understanding. The validity of the method is analyzed through both word decoding/identifying models and text understanding models. On the basis of quantitative and qualitative data analyses of the tests passed by sixty-eight first grade children, we show the interest of an evaluation method that combines several tests, including two for autonomous understanding of a written text, in order to assess children reading skills and to identify the different types of difficulties they can encounter

One-pot homologation of boronic acids : a platform for diversity-oriented synthesis

Formal homologation of sp2-hybridized boronic acids is achieved via cross-coupling of boronic acids with conjunctive haloaryl BMIDA components in the presence of a suitably balanced basic phase. The utility of this approach to provide a platform for diversity-oriented synthesis in discovery medicinal chemistry is demonstrated in the context of the synthesis of a series of analogues of a BET bromodomain inhibitor

One-pot homologation of boronic acids : a platform for diversity-oriented synthesis

Formal homologation of sp2-hybridized boronic acids is achieved via cross-coupling of boronic acids with conjunctive haloaryl BMIDA components in the presence of a suitably balanced basic phase. The utility of this approach to provide a platform for diversity-oriented synthesis in discovery medicinal chemistry is demonstrated in the context of the synthesis of a series of analogues of a BET bromodomain inhibitor

Enantiodivergent Formation of C−P Bonds: Synthesis of P‑Chiral Phosphines and Methylphosphonate Oligonucleotides

Phosphorus Incorporation (PI, abbreviated Π) reagents for the modular, scalable, and stereospecific synthesis of chiral phosphines and methylphosphonate nucleotides are reported. Synthesized from translimonene oxide, this reagent class displays an unexpected reactivity profile and enables access to chemical space distinct from that of the Phosphorus−Sulfur Incorporation reagents previously disclosed. Here, the adaptable phosphorus(V) scaffold enables sequential addition of carbon nucleophiles to produce a variety of enantiopure C−P building blocks. Addition of three carbon nucleophiles to Π, followed by stereospecific reduction, affords useful P-chiral phosphines; introduction instead of a single methyl group reveals the first stereospecific synthesis of methylphosphonate oligonucleotide precursors. While both Π enantiomers are available, only one isomer is requiredthe order of nucleophile addition controls the absolute stereochemistry of the final product through a unique enantiodivergent design

Spectroscopic studies of the Chan-Lam amination : a mechanism-inspired solution to boronic ester reactivity

We report an investigation of the Chan-Lam amination reaction. A combination of spectroscopy, computational modeling, and crystallography has identified the structures of key intermediates and allowed a complete mechanistic description to be presented, in-cluding off-cycle inhibitory processes, the source of amine and organoboron reactivity issues, and the origin of competing oxida-tion/protodeboronation side reactions. Identification of key mechanistic events has allowed the development of a simple solution to these issues: manipulating Cu(I)→Cu(II) oxidation and exploiting three synergistic roles of boric acid has allowed the development of a general catalytic Chan-Lam amination, overcoming long-standing and unsolved amine and organoboron limitations of this valuable transformation

Human γδ T cells recognize CD1b by two distinct mechanisms

γδ T cells form an abundant part of the human cellular immune system, where they respond to tissue damage, infection, and cancer. The spectrum of known molecular targets recognized by Vδ1-expressing γδ T cells is becoming increasingly diverse. Here we describe human γδ T cells that recognize CD1b, a lipid antigen-presenting molecule, which is inducibly expressed on monocytes and dendritic cells. Using CD1b tetramers to study multiple donors, we found that many CD1b-specific γδ T cells use Vδ1. Despite their common use of Vδ1, three CD1b-specific γδ T cell receptors (TCRs) showed clear differences in the surface of CD1b recognized, the requirement for lipid antigens, and corecognition of butryophilin-like proteins. Several Vγ segments were present among the CD1b-specific TCRs, but chain swap experiments demonstrated that CD1b specificity was mediated by the Vδ1 chain. One of the CD1b-specific Vδ1+ TCRs paired with Vγ4 and shows dual reactivity to CD1b and butyrophilin-like proteins. αβ TCRs typically recognize the peptide display platform of MHC proteins. In contrast, our results demonstrate the use of rearranged receptors to mediate diverse modes of recognition across the surface of CD1b in ways that do and do not require carried lipids

One-pot homologation of boronic acids

This work was supported by the Engineering and Physical Sciences Research Council (EPSRC).Formal homologation of sp2-hybridized boronic acids is achieved via cross-coupling of boronic acids with conjunctive haloaryl BMIDA components in the presence of a suitably balanced basic phase. The utility of this approach to provide a platform for diversity-oriented synthesis in discovery medicinal chemistry is demonstrated in the context of the synthesis of a series of analogues of a BET bromodomain inhibitor.Publisher PDFPeer reviewe