Metallo-boranes: A class of unconventional superhalogens defying electron counting rules

Superhalogens are a class of highly electronegative atomic clusters whose electron affinities exceed those of halogens. Due to their potential for promoting unusual reactions and role as weakly coordinating anions...

Desain Didaktis Materi Kaidah Pencacahan Untuk Siswa SMA Kelas XI

This study aims to develop didactic design on counting rules for senior high school. The didactic design is designed by considering two things the result of the test analysis of learning obstacle instrument and learning trajectory. This didactic design consists of four meetings obtained through the three formal stages performed in the study. The first stage is prospective ie didactic situation analysis before learning in the form of hypothetical didactic design including pedagogical didactic anticipation (ADP), second phase metaped analysis is notthe form of design implementation phase, and last stage is retrospective analysis which is an analysis that relate result of prospective analysis with metaped analysis nottik used to formulate empirik design. The research for preparing the didactic design begins with the provision of difficulties in learning the material of the counting rules and the analysis of the teaching materials. The results of the learning obstacle test show that students experience learning barriers that are categorized into three, namely ontogenic obstacle, didactical obstacle, and epistemological obstacle. The didactic design was implemented to 35 students of class XI in one of the senior high school in South Jakarta. Based on the results of research, didactic design developed this can be used as an alternative teaching materials concept of counting rules to minimize student learning barriers.

The Relationship Between Confidence and Conformity in a Non-routine Counting Task With Young Children: Dedicated to the Memory of Purificación Rodríguez

Counting is a complex cognitive process that is paramount to arithmetical development at school. The improvement of counting skills of children depends on their understanding of the logical and conventional rules involved. While the logical rules are mandatory and related to one-to-one correspondence, stable order, and cardinal principles, conventional rules are optional and associated with social customs. This study contributes to unravel the conceptual understanding of counting rules of children. It explores, with a developmental approach, the performance of children on non-routine counting detection tasks, their confidence in their answers (metacognitive monitoring skills), and their ability to change a wrong answer by deferring to the opinion of a unanimous majority who justified or did not justify their claims. Hundred and forty nine children aged from 5 to 8 years were randomized to one of the experimental conditions of the testimony of teachers: with (n = 74) or without justification (n = 75). Participants judged the correctness of different types of counting procedures presented by a computerized detection task, such as (a) pseudoerrors that are correct counts where conventional rules are violated (e.g., first counting six footballs, followed by other six basketballs that were interspersed along the row), and (b) compensation errors that are incorrect counts where logical rules were broken twice (e.g., skipping the third element of the row and then labeling the sixth element with two number words, 5 and 6). Afterwards, children rated their confidence in their detection answer with a 5-point scale. Subsequently, they listened to the testimony of the teachers and showed either conformity or non-conformity. The participants considered both compensation errors and pseudoerrors as incorrect counts in the detection task. The analysis of the confidence of children in their responses suggested that they were not sensitive to their incorrect performance. Finally, children tended to conform more often after hearing a justification of the testimony than after hearing only the testimonies of the teachers. It can be concluded that the age range of the evaluated children failed to recognize the optional nature of conventional counting rules and were unaware of their misconceptions. Nevertheless, the reasoned justifications of the testimony, offered by a unanimous majority, promoted considerable improvement in the tendency of the children to revise those misconceptions.

Magnetic shielding paints an accurate and easy-to-visualize portrait of aromaticity

Chemists are trained to recognize aromaticity semi-intuitively, using pictures of resonance structures and Frost-Musulin diagrams, or simple electron-counting rules such as Hückel’s 4n + 2/4n rule. To quantify aromaticity one...