基于计算机探究性建模的高中化学“反应速率”教学设计*

模型和建模是化学核心素养的重要组成部分。计算机辅助建模具有可视化性,能创设探究性学习环境,在教师引导学生构建模型和学习概念中扮演着重要角色。基于计算机辅助建模的优势,开展注重学生参与度、由学生自主建模的探究性教学。以“化学反应速率”为例,选择计算机建模工具SageModeler作为辅助技术,围绕心智模型的建立、评价、发展和优化,旨在通过建模教学提高学生对模型本质的理解,发展学生建模的观念和能力,形成对化学反应速率的清晰认识。     

“原子结构与元素性质”主题模型建构教学的探索

从2003年起至今,北京师范大学化学教育研究团队围绕“原子结构与元素性质”主题开展了跨越初中、高中必修、高中选择性必修的模型建构教学探索,涉及原子的构成微粒及空间分布、核外电子的运动状态、核外电子的排布规律以及元素性质等不同子主题。在这些教学探索中,梳理和还原了科学家解决问题的过程,对科学家所做实验进行再现、模拟,依据科学家在基于实验证据建构原子结构模型时的推理论证过程设计并指导学生开展模型建构活动,使学生理解、评价或参与模型建构的过程,促进学生建模能力和科学本质观的形成与发展。     

化学教师模型认识与模型教学观的关系研究*

主要使用李克特式量表问卷测查了256名中学化学教师的模型认识与模型教学观的结构与水平,并使用结构方程模型进一步探查化学模型认识与模型教学观的关系。结果表明:(1)化学教师对化学模型的描述与解释功能以及模型的暂定性具有较好的认识,但对模型预测功能认识不足;(2)化学教师在模型教学中倾向于使用模型描述、解释或预测化学现象,并且较认可以学生为中心的模型教学,但缺乏对模型暂定性的反思;(3)化学教师的模型认识基本上可预测其模型教学观,如关于模型功能的认识能显著预测其模型教学观。文末据此为我国化学教师培训及其研究提出相关建议。     

发展“模型认知”素养的教学实践*——以“化学方程式”为例

模型认知是重要的思维方法。基于模型认知进行教学设计,能促使教师从关注知识转向关注核心素养,从而使教学活动有效地促进学生思维能力的发展。在对模型及模型认知理解的基础上,以典型的符号模型“化学方程式”为例,阐明了教学思路和教学活动与学科观念的关系,形成了发展学生模型认知核心素养的教学设计。     

基于模型与建模的化学学习过程设计

在阐释模型分类、模型功能和建模学习的意义的基础上,以“浓度对化学反应速率的影响”之学习过程设计为例,说明在化学教学中通过确立建模目标、模型参数选择、模型建构及表征、分析、评价、调用、重构等活动,可有效提升学生心智模型与表达模型的内在一致性和有效性,促进学生对化学知识的有效探究和深度理解。     

基于雨课堂+企业微信+慕课的在线直播教学——以有机化学为例

主要介绍了基于雨课堂和企业微信双平台直播教学,以及同步慕课课程为辅的有机化学在线教学实践,并以教学实例展示了"学生为中心,教师为引导"的"疑探"式教学体系.该在线直播教学还融入以弹幕、微信群和小组作业为主的交互方式,注重学生与学生、学生与教师以及学生与教学资源的互动;通过构建多维度的考核体系,加强对学习过程的考核,提高...     

聚合物流变学教学中的几点体会

针对聚合物流变学多学科交叉性以及较强的理论性和实践性的特点,结合作者的教学实践,总结了在聚合物流变学教学中的几点体会。提出在该门功课讲授过程中注重教学内容与教学方法的形象化,培养学生的学习兴趣;通过开设实验课,放映实践过程录像、图片等形式将理论与实践结合的教学方法,消除学生学习该门课程的抽象感。此外,通过教学实例提出在...     

元素周期律复习教学中认识模型建构的有效策略

探查了元素周期律复习教学中认识模型构建的有效策略。从学生对于元素周期律的学后障碍点及相应的发展核心入手,在北京市选择了2所学生水平不同的学校分别进行了2课时的元素周期律复习教学。教学过程中基于学生认识发展的核心,选取了不同的模型构建组织策略,通过进阶式的教学任务对元素周期律的“位置-结构-性质”认识模型和物质性质的认识模型进行了构建。在问卷测查以及将本研究授课效果与常规授课进行对比后,证明并提炼了基于模型构建的元素周期律复习教学的有效策略。     

基于分子间相互作用的DNA双螺旋结构的启发式教学

实践教学中发现很多学生片面地认为是氢键作用使DAN形成双螺旋结构,面对这一认知的误区,设计了启发式的教学过程。从分子间相互作用力的角度分析讨论了为什么DNA通常会形成双螺旋结构以及有哪些相互作用在结构的形成中起到了关键性作用。课程从铺陈、问题启发式讨论及拓展3方面层层深入展开。通过此教学过程,不仅加深了学生对化学基本原理的理解,而且也培养了学生分析和解决问题的能力。     

高等师范院校“化学史”教学的探讨

“化学史”是高等师范院校为化学（教育）专业学生开设的一门专业选修课,但长期以来对于该门课程的教学研究不够重视。经过近几年的教学实践,在“化学史”教学过程中采用分段教学与过程评价,即参与型教学、学生试讲、学生论文及学生过程评价,取得了较好的教学效果。     

“分子三维模型制作”劳动技能课线上线下混合式教学设计与实践*

改进了大学化学类专业劳动技能课“分子三维模型制作”,并提出线上线下混合教学模式和多元化考核方式相结合的实践教学思路与方法。在课程中引入生产实例、学科前沿和时事热点进行创新创业和思政教育,积极引导学生主动参与实践教学,充分调动学生的劳动兴趣,以适应新时期培养创新性劳动者的需要。     

Wire-Arc Spray Modeling

A model is presented describing the details of the wire-arc spray process. The model consists of several submodels each treating a different part of the process. A compressible flow model describes the supersonic nozzle flow upstream of the wire tips. The arc is described by a 3-D arc in cross-flow model using different boundary conditions for the cathode and the anode boundary. The resulting temperature and velocity contours serve as upstream boundary for a 2-D turbulent jet model. Particle generation and acceleration is described by treating the initial droplet formation for the anode and the cathode wire separately and then using the resulting particle size and velocity distributions in a secondary break-up model. Comparison with some experimental results show acceptable agreement. This modeling approach may be used for optimization of wire-arc spray equipment.     

Modeling robust QSAR

Quantitative Structure Activity Relationship (QSAR) is a term describing a variety of approaches that are of substantial interest for chemistry. This method can be defined as indirect molecular design by the iterative sampling of the chemical compounds space to optimize a certain property and thus indirectly design the molecular structure having this property. However, modeling the interactions of chemical molecules in biological systems provides highly noisy data, which make predictions a roulette risk. In this paper we briefly review the origins for this noise, particularly in multidimensional QSAR. This was classified as the data, superimposition, molecular similarity, conformational, and molecular recognition noise. We also indicated possible robust answers that can improve modeling and predictive ability of QSAR, especially the self-organizing mapping of molecular objects, in particular, the molecular surfaces, a method that was brought into chemistry by Gasteiger and Zupan.     

Modeling styrene-styrene interactions

This study is the first step in the systematic investigation of substituted (carboxyl) polystyrene nanoparticles. Understanding the fundamental interactions between the p-carboxyl styrene monomers, where an ethyl group is used instead of a vinyl group (referenced, for convenience, as "p-carboxyl styrene"), provides the basic information needed to construct potentials for nanoparticles composed of these monomers. In this work, low-energy isomers of p-carboxyl styrene dimer were studied. The dimer structures and their relative and binding energies were determined using both M?ller-Plesset second-order perturbation theory (MP2) and the general effective fragment potential (EFP2) method. Sections of the intermolecular potential energy surface (PES) of the p-carboxylated styrene dimer in its global minimum orientation were also determined. As expected, double hydrogen bonding between the two carboxylic groups provides the strongest interaction in this system, followed by isomers with a single H-bond and strong benzene ring-benzene ring (pi-pi) type interactions. Generally, the EFP2 method reproduces the MP2 geometries and relative energies with good accuracy, so it appears to be an efficient alternative to the correlated ab initio methods, which are too computationally demanding to be routinely used in the study of the more-complex polymeric systems of interest.     

Modeling inverse microemulsion polymerization

A mathematical model for inverse microemulsion polymerization has been developed. The model has been used to fit experimental results of the effect of initiator concentration, light intensity, emulsifier concentration, and dispersed phase weight fraction on the monomer conversion evolution, particle size, and polymer molecular weight in the inverse microemulsion polymerization of 2-methacryloyl oxyethyl trimethyl ammonium chloride (MADQUAT) initiated by UV light in the presence of AIBN. A good fitting of the experimental data was achieved. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2167–2178, 1999     

Modeling stable free-radical polymerization

A kinetic model has been developed for stable free-radical polymerization (SFRP) processes by using the method of moments. This model predicts monomer conversion, number-average molecular weight, and polydispersity of molecular weight distribution. The effects of the concentrations of initiator, stable radical, and monomer, as well as the rate constants of initiation, propagation, termination, transfer, and the equilibrium constant between active and dormant species, are systematically investigated by using this model. It is shown that the ideal living-radical polymerization having a linear relationship between number-average molecular weight and conversion and a polydispersity close to unity is the result of fast initiation, slow propagation, absence of radical termination, and a high level of dormant species. Increasing stable radical concentration helps to reduce polydispersity but also decreases polymerization rate. Thermal initiation significantly broadens molecular weight distribution. Without the formation of dormant species, the model predicts a conventional free-radical polymerization. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2692–2704, 1999     

Modeling force-induced bio-polymer unfolding

We study the conformations of polymer chains in a poor solvent, with and without bending rigidity, by means of a simple statistical mechanics model. This model can be exactly solved for chains of length up to N = 55 using exact enumeration techniques. We analyze in detail the differences between the constant force and constant distance ensembles for large but finite N. At low temperatures, and in the constant force ensemble, the force–extension curve shows multiple plateaus (intermediate states), in contrast with the abrupt transition to an extended state prevailing in the N → ∞ limit. In the constant distance ensemble, the same curve provides a unified response to pulling and compressing forces, and agrees qualitatively with recent experimental results. We identify a cross-over length, proportional to N, below which the critical force of unfolding decreases with temperature, while above, it increases with temperature. Finally, the force–extension curve for stiff chains exhibits “saw-tooth” like behavior, as observed in protein unfolding experiments.