Preservice teachers’ use of contrasting cases in mathematics instruction

Drawing comparisons between students’ alternative solution strategies to a single mathematics problem is a powerful yet challenging instructional practice. We examined 80 preservice teachers’ when asked to design a short lesson when given a problem and two student solutions—one correct and one incorrect. These micro-teaching events were videotaped and coded, revealing that fewer than half of participants (43%) made any explicit comparison or contrasts between the two solution strategies. Those who did were still not likely to use additional support strategies to draw students’ attention to key elements of the comparison. Further, correlations suggest that participants’ mathematical content knowledge may be related to whether participants’ showed contrasting cases but not to whether they used specific pedagogical cues to support those comparisons. While these micro-teaching events differ from the interactive constraints of a classroom, they reveal that participants did not immediately orient toward differing student solutions as a discussion opportunity, and that future instruction on contrasting cases must highlight the utility of this practice.     

论法律漏洞存在的原因、类型及其防治

法律漏洞指法律中的缺漏和矛盾。其存在有两个原因:法律自身及其调整的社会关系方面的原因和立法者方面的原因。法律漏洞可分为形式漏洞与实质漏洞。可从两方面消除或减少它:立法角度防止其产生和司法角度弥补。法律中存在漏洞虽影响法律的效度和信度,但对法制的完备也有重要作用。     

试析邓小平理论的时代特色

本文基于学习《邓小平文选》第三卷的体会,试图从开放性、开拓性、独立性、辩证性、唯实性和群众性等六个方面剖析邓小平理论的时代特色,对建设有中国特色社会主义的理论和实践具有深刻的教益和启义。     

Edison仿真分析在电学实验中的应用

介绍了Edison仿真软件的使用方法和特点，阐明了该软件在中学电学实验中应用的可行性，并结合具体实例得出实际应用中需注意的相关问题。     

纯液体常沸点汽化热的简单计算

在文献[1]的基础上,引入Pitzer三参数对比状态普遍化关系式和Edmister方程式,由最基本的物性数据T_b、T_c和安托固常数计算了25种物质的常沸点汽化热。计算值与实验值间的平均相对误差小于±1％。     

经合组织发展跨境高等教育的策略及我国的对策

跨境高等教育由学生和教师、项目课程、教育机构这三个方面的跨境流动来进行。由于国际学生的流动人数众多,招收外国学生不仅有利于加强国家间文化、政治、贸易、经济关系的长期发展,提升国家的竞争力,更有利于提高国家的财政收入。笔者从经合组织与我国学生跨境高等教育的现状入手,分析了发展跨境高等教育的必要性,并从经合组织及其成员国的宏观政策对发展学生跨境教育的作用进行了分析。通过比较研究,提出了我国在宏观层面上发展学生跨境高等教育可选择的对策。     

三科教材中的历史英雄人物:基于数据的研究

对中华人民共和国成立以来人教版十套教材和课改后多版本教材德育、语文、历史等学科教材中出现的历史英雄人物及其分类、出现频次、学科分布、学段分布、时代分布的大规模量化研究,可以发现革命领袖一直是各个时期教材中出现频率最高的英雄类别,但其他类别的历史英雄人物在不同时期出现频次占比次序各有不同。除岳飞、林则徐、毛泽东、鲁迅、雷锋等少数历史英雄人物各套别和版本分布特征相似度较高外,不同套别和版本教材中各类型历史英雄人物分布特征各异。建议新时期统编三科教材保证重点历史英雄人物及其内容的篇幅,保证各类型历史英雄人物的平衡分布。     

Infrared Absorption Spectra of Serpentine Cat＇s Eye from Sichuan Province of China

Infrared （IR） absorption spectra and X-ray powder diffraction （XRD） patterrns of sexpenfine cat＇s eye from Sichuan Province have been investigated, and infrared absorption bands of the serpentine have been assigned in this paper. The results indicate that the bands near 3 600 - 3 700 cm^-1 belong to the stretching absorption band VOH, the bands in 948 - 1 100 cm^-1 axe assigned to the stretching vibraling band Usvo, and the bands at 600 570 and 440 cm^-1 respectively belong to the bending vibration band VOH, δMg-O and δSi-O. The serpentine cat＇ s eye includes two types： chrysotile and antigorite. Chrysotile has a sharp and intensive band at 3 688 cm^-1 and a weak band at 3 643 cm^-1 , while antigorite has only one intensive band in the region. At vibration band VSi-O, chrysotile and antigorite have a similar feature at 1 071 cm^-1, but the band at 980 cm^-1 in anfigorite has been split into two bands in chrysotile - a strong one at 1 027 cm^-1 and a weak one at 949 cm^-1. In addition, antigorite has a characteristic bending vibrating band δMg-O at 570 cm^-1. Based on the analysis of the feature of crystal structure, their IR differences axe well explained.     

无机化学反应中的耦合现象

若一个化学反应的ΔγGθm >0 ,从热力学角度可以确定该反应在标准状态下不能自发进行 .改变反应条件 ,该反应可以转向自发也可能仍不能自发进行 ,在不改变其它反应条件下 ,利用一个能释放大量自由能的反应与之耦合 ,便可达到转化的目的 ,这就是化学反应中的耦合现象 .耦合现象与反应的能量密切相关