国际科学教育视角下1-9年级学生“物质”核心概念进阶维度研究

概念转变理论、认知架构理论、概念形成理论都验证了核心概念建构的重要性。基于核心概念建构的进阶路径,介绍了学生理解“物质”概念进阶表征框架、“物质”和学生能力水平进阶表征框架、“物质”结构的学习进阶表征框架、“物质”核心概念区块理论表征框架和“物质”概念描述理论表征框架,并以“水的认识”为例分析了其构造图和结果空间。基于美国、英国、澳大利亚、爱尔兰、新加坡、加拿大阿尔伯塔省、加拿大安大略省、中国台湾、中国大陆9个国家或地区1至9年级科学课程文件,梳理了学生“物质”核心概念,并从“成分与辨识”“性质与应用”“变化与转化”3个视角划分了学生“物质”核心概念进阶维度,介绍了“物质”核心概念进阶测量方法,以期对我国科学教育有所启示。     

“素养为本”的化学课堂教学*——以“原子晶体”为例

基于“素养为本”视角,以“原子晶体”的教学为例,对教学主题内容、教学现状及学情进行分析;以发展学生化学学科核心素养为主旨确定教学目标;以“微粒-微粒间的相互作用-物质的聚集状态-物质性质”的认识思路为主线,以“模型认知,建构概念-证据推理,归纳性质-微观探析,探究结构-科学史实,揭示价值”的任务型教学流程,达到落实并发展学生化学学科核心素养的目的。     

日本初中理科教科书中“粒子的存在”内容选择及启示

日本理科课程中“粒子”科学概念主要与化学课程相关,“粒子的存在”是“粒子”的首要核心概念,主要发展学生从微观层面认识物质的性质、结构及2者之间关系的能力,明确物质是由粒子构成的,粒子包括分子、原子和离子等,且粒子的性质决定物质的性质。从“重要事实”“核心内容”和“主要观念”3个方面自下而上对日本《新科学》教科书中“粒子的存在”相关内容的选择进行分析,发现《新科学》教科书在内容选择上具有注重“粒子模型”构建的层次性和观念层面要求显性化的特征。     

高中化学“乙醛性质”的项目式教学*——解酒药的研制

以“解酒药的研制”为项目主题,开展高中化学“乙醛性质”的教学。学生通过完成“药物研发分析”“探秘致命物质,寻找救治办法”“药物新构想”等3个项目任务,掌握了乙醛的性质及其应用,构建了有机物结构分析和性质预测的思维模型,学会了对陌生有机物的分析与研究。运用手持技术数字化实验测定溶液酸碱性确定反应机理,锻炼了科学探究、合作交流、思维表达的能力。与课外活动有效整合、实验室仪器与试剂的保障、资料查阅、外援专家指导等是顺利完成本项目教学的关键。     

以实验和论证为杠杆撬动化学概念深度学习*——以“分子与原子”教学为例

以倡导“理解与批判、联系与构建、迁移与应用”的深度学习为理念,围绕“分子与原子的概念”比较教材与文献的设计思路,调整认知脉络,着力解决“概念学习过程中实验探究少,宏观现象进入微观分析的相关实验不匹配,忽略证据推理、变化观念与平衡思想核心素养”等不足。设计“3种形态的碘与淀粉的反应、H2O2溶液与品红反应、H2O2溶液的分解反应”3组实验,设置学生画分子模型、画H2O2分子分解的微观过程等活动,提炼“物质种类、分子种类、物质性质之间的关系是什么？你从实验中找到哪些证据支持观点？前2个单元的实验,还有哪些可作为论证的依据？”等问题,引发学生充分论证。“实验、活动、问题、论证”环环相扣,促成教学内容的有效结构化,通过化学概念的深度学习实现化学学科核心素养的发展。     

中学生对“溶液”概念理解的可视化表征及启示

学生概念理解的可视化表征可以通过学生的作图来展示,分析图示可以获取学生概念理解的更加深入的信息。梳理了国内外有关中学生对“溶液”概念理解的研究,集中对学生的作图进行分析,呈现了中学生对“溶液”概念理解的可视化表征。针对作图发现的学生概念理解的结果,提出了促进中学生“溶液”概念理解的教学启示。     

基于“教学评一体化”的化学探究活动一般思路方法建构*——以“物质的分离与提纯”复习课为例

针对学生面对化学实验探究问题无从下手的情况,以物质的分离与提纯这一类探究实验为例,通过“教学评一体化”的教学模式引导学生建立解决“物质分离与提纯”探究实验的一般思路方法。     

高中生“芳香烃”心智模型的测评及其教学启示*

采用二阶式纸笔测验以及半结构化访谈法对高中生持有的“芳香烃”心智模型进行测评,并重点分析了学生建构的与“芳香烃和苯的同系物的概念”“芳香烃的结构”“苯及其同系物的化学性质”等概念群相关的缺陷模型。研究发现学生建构的有关“芳香烃”缺陷模型包括3大类共计11种;学生对有机物空间结构的想象力和建构能力较为薄弱;学生对“有机化合物结构内基团之间相互作用对其化学性质的影响”认识不足,“性质结构”模型不完善;学生建构的有机化学的心智模型尚不具备整体性。     

高中生对化学核心概念掌握情况的测查分析——以“电解质、离子反应、化学键”概念群为例

电解质、离子反应、化学键组成一个核心概念群,是学生掌握相关知识的重难点。对北京市普通高中370名高二学生的测查显示:(1)概念掌握的程度为:化学键<离子反应<电解质。(2)“电解质的概念”与“导电原理”“离子反应概念”“离子共存”的掌握程度存在显著相关;电离与离子反应概念的掌握程度显著相关;“导电原理”与“离子反应概念”“离子共存”“离子键与共价键综合辨析”的掌握程度显著相关。表明电解质的概念、导电原理的理解与掌握是概念体系中的重要纽带。(3)优秀、中等、学困3类学生在解决容易和较难2类概念的相关问题上差异最大,而中等难度上的差异相对较小。基于此,提出了相应的核心概念教学对策。     

基于真实情境的初中化学微项目教学实践与反思*——以“溶液的形成”为例

以“溶液的形成”为例进行微项目教学实践,选择学生熟悉的护手霜为主题情境,巧妙设计了“原料分散”“微观探秘”“辨识活动”“对比实验”“感知乳化”等系列微项目活动,通过情境不断地设置认知冲突,引导学生反思、修正并最终形成更完善的概念,在环环相扣的探究活动中使学生自主建构结构化的知识。通过制作“护手霜”将“溶解”和“乳化”串联,感知溶液,感受乳化,感悟人与自然、社会的和谐、可持续发展。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.