用三角方法解几何题

有些几何问题,用三角方法来解比较容易。举例如下: [例1] 求证:平行四边形对角线平方的和,等于四边平方的和。思路只要用三角方法,计算出两条对角线的平方,看它们的和是不是等于四边平方的和。这里,要用到∠DAB与∠ABC互补的关系。证明如图1,ABCD为平行四边形     

诗词中的沧海桑田

浪淘沙 白浪茫茫与海连,平沙浩浩四边无。 朝去暮来淘不住,遂令东海变桑田。 释义：白浪一望无边,与海相连,岸边的沙子也是一望无际。日复一日,年复一年。海浪从不停歇地淘着沙子,于是沧海桑田的演变就这样出现。     

四边形边长范围的求法

当一个四边形中已知其中三边时，不能求出第四边的具体长度，但可以得出第四边的取值范围．本文选取数例，与同学们共同寻找此类问题的解法．     

思想品德课"四边"课堂教学模式初探

“四边”课堂教学模式,就是在课堂教学中做到“边学、边导、边练、边讲”。“学生边学边练,教师边导边教”是“四边”的最大特点。它明确地要求教师做到以下三点：     

词牌妙趣

词牌名目繁多且绚丽多彩,如分类欣赏,更有一番情趣。数字传神一剪梅、二郎神、三姝媚、四边静、五样锦、六丑、统七贤、八声甘州、九张机、十五郎、十六字令、百花开、千秋岁、万年欢。浪漫情调声声慢、步步娇、齐天乐、     

四边简支弯曲振动方形薄板辐射阻抗及辐射声功率的研究

从振速分布不均匀振动面辐射阻抗的定义出发,推导了不同模态的四边简支方形薄板以中心点振速为参考的辐射阻抗表达式,研究了弯振方形板辐射阻抗对辐射声功率的影响。结果表明：对于四边简支方形薄板,当中心点振速一定时,在中低频段,模态越低,对应的辐射阻越大,因而辐射声功率也越大。四边简支的弯振方形板的辐射声功率主要由其低模态的声功率决定。     

汉字笔形变化口诀

书写汉字,必须掌握间架结构和笔形变化规律。一般注意间架结构的多,注意笔形变化规律的少;如果两者都能掌握,写出字来必然方正、紧凑,体态多姿。在写字教学中,有人把汉字笔形变化规律编成口诀帮助学生记忆。方块汉字四边齐,     

弹性地基上四边自由矩形大挠度薄板的自由振动

考虑具有粘滞阻尼的Winkler地基上四边自由受简谐激励的矩形板的偏微分方程组,找到了满足所有边界条件的近似挠度函数,利用Galerkin方法把偏微分方程表示的非线性动力学方程转化为用常微分方程表示的非线性动力学方程。在KBM法的基础上,引入谐波平衡的观点研究了弹性地基上四边自由无阻尼矩形板自由振动,应用Hamiltonion函数研究了系统能量与周期的关系。     

自制风车六例

1.将铅画纸剪成正方形,在上面画幼儿喜爱的图案。 2.折出对角线,在中心点上钻一个小洞,找出四边的中线(图1)。 3.在四边的中线处剪一刀并折起(图2)。     

梯形的四边关系及应用

我们知道,三角形三边关系:两边之和大于第三边,两边之差小于第三边。那么,四边形的四条边是否也应满足某一关系呢?问题显然是肯定的.下面让我们来探究一下梯形的四边关系.     

反真实材质在三维教学动画中的应用探索

计算机三维动画在中小学及高校的学科教学中发挥着重要的作用,以往的教学三维动画的画面大多采用写实的风格,随着技术的发展,出现了反真实(卡通型)材质,它突出简约的色彩层次和鲜明的轮廓线条,为创作二维动画风格的三维动画提供了条件。本文探讨的就是如何利用反真实(卡通)材质的特点,设计风格新颖的教学动画。     

Integrating Model-Based Learning and Animations for Enhancing Students’ Understanding of Proteins Structure and Function

This paper describes a study conducted in the context of chemistry education reforms in Israel. The study examined a new biochemistry learning unit that was developed to promote in-depth understanding of 3D structures and functions of proteins and nucleic acids. Our goal was to examine whether, and to what extent teaching and learning via model-based learning and animations of biomolecules affect students’ chemical understanding. Applying the mixed methods research paradigm, pre- and post-questionnaires as well as class-observations were employed in the collection, analysis, and interpretation of data. The research population included 175 grade twelve students, divided into three research groups: (a) hands-on exploration of animations, (b) teacher’s demonstrations of animations, (c) traditional learning using textbooks. Findings indicated that the integration of model-based learning and 3D animations enhanced students’ understanding of proteins’ structure and function and their ability to transfer across different levels of chemistry understanding. Findings also indicated that teachers’ demonstrations of animations may enhance students’ ‘knowledge’—a low order thinking skill; however, in order to enhance higher levels of thinking, students should be able to explore 3D animations on their own. Applying constructivist and interpretative analysis of the data, three themes were raised, corresponding to cognitive, affective, and social aspects of learning while exploring web-based models and animations.     

工程制图仿真系统设计

工程制图仿真系统由多个独立的课件或素材库构成。利用AutoCAD软件进行三维实体造型 ,再利用 3DSMAX软件制作三维动画 ,充分运用色彩、自动旋转、切割、叠加、剖切、拆装和透明等效果 ,图片及动画均制作成JPG或GIF格式。动画在 3DMAX软件中保存为AVI格式 ,然后通过豪杰软件压缩为MPEG格式 ,再转化为GIF格式 ,以使仿真系统用于网上运行     

Animated cell biology: a quick and easy method for making effective, high-quality teaching animations

There is accumulating evidence that animations aid learning of dynamic concepts in cell biology. However, existing animation packages are expensive and difficult to learn, and the subsequent production of even short animations can take weeks to months. Here I outline the principles and sequence of steps for producing high-quality PowerPoint animations in less than a day that are suitable for teaching in high school through college/university. After developing the animation it can be easily converted to any appropriate movie file format using Camtasia Studio for Internet or classroom presentations. Thus anyone who can use PowerPoint has the potential to make animations. Students who viewed the approximately 3-min PowerPoint/Camtasia Studio animation "Calcium and the Dual Signalling Pathway" over 15 min scored significantly higher marks on a subsequent quiz than those who had viewed still graphics with text for an equivalent time. In addition, results from student evaluations provided some data validating the use of such animations in cell biology teaching with some interesting caveats. Information is also provided on how such animations can be modified or updated easily or shared with others who can modify them to fit their own needs.     

Using “Slowmation” to Enable Preservice Primary Teachers to Create Multimodal Representations of Science Concepts

Research has identified the value of students constructing their own representations of science concepts using modes such as writing, diagrams, 2-D and 3-D models, images or speech to communicate meaning. ??Slowmation?? (abbreviated from ??Slow Animation??) is a simplified way for students, such as preservice teachers, to make a narrated animation using a combination of modes. In this study, 13 preservice primary teachers learned how to create a slowmation during a two-hour class in a science methods course and then created one about an allocated science topic as an assignment. The research question that guided this study was, ??What are the preservice teachers?? perceptions of making a slowmation and how was the science concept represented in the animation??? Data included pre and post individual interviews, concept maps constructed during the interviews and the animations as artifacts. Three case studies provide a window into the perceptions of preservice teachers making a slowmation and show how they represented their concept. Slowmation is a new form of student-generated representation which enables them to use their own technology to construct a narrated animation as a multimodal representation to explain a science concept.     

Towards a Framework for Attention Cueing in Instructional Animations: Guidelines for Research and Design

This paper examines the transferability of successful cueing approaches from text and static visualization research to animations. Theories of visual attention and learning as well as empirical evidence for the instructional effectiveness of attention cueing are reviewed and, based on Mayer’s theory of multimedia learning, a framework was developed for classifying three functions for cueing: (1) selection—cues guide attention to specific locations, (2) organization—cues emphasize structure, and (3) integration—cues explicate relations between and within elements. The framework was used to structure the discussion of studies on cueing in animations. It is concluded that attentional cues may facilitate the selection of information in animations and sometimes improve learning, whereas organizational and relational cueing requires more consideration on how to enhance understanding. Consequently, it is suggested to develop cues that work in animations rather than borrowing effective cues from static representations. Guidelines for future research on attention cueing in animations are presented.     

渤海曹妃甸LNG码头布置的潮流数值模拟(英文)

为了在大范围数学模型中合理有效地模拟码头桩基等小尺度建筑物附近的潮流场,采用非结构网格建立了渤海二维有限元潮流数学模型.在面积达85 700 km2的模型范围中将码头桩基概化为面积约20-30 m2的不透水单元,用于直接模拟桩基附近的复杂潮流场.在此基础上,对渤海曹妃甸海域10万吨级LNG(液化天然气)码头布置的走向进行了优化.结果表明:数学模型模拟的潮位和流速等水动力特征与实测结果一致,LNG码头布置的优化结果合理可信.表明建立的能够直接模拟小尺度建筑物的渤海二维有限元数学模型可应用于码头工程布置及优化的潮流场模拟研究.     

医学教育中计算机动画应用的文献回顾

计算机动画可以显示动态的变化,表达抽象的概念,因此医学教育中越来越多地应用计算机动画。然而,动画的优越性会因学习者个体差异如知识储备和空间认知能力的不同而不同,动画并非一直有效。本文介绍了相关的研究成果,描述了动画在医学教育中的应用,根据认知负荷理论为动画的设计和使用提供了原则,为未来研究提供了方案。     

Effects of Animations in Learning—A Cognitive Fit Perspective1

Information technology (IT) artifacts such as animations are increasingly used in educational institutions. Researchers caution that, if we are to derive benefits from animations and other such IT artifacts, we must understand how to use it optimally. In this study, we look at the effects of animations in supporting learning processes. IT‐enabled animations dynamically depict changes in events and are used in the classroom as external representations to elaborate on the knowledge content transferred in the classroom. Research in related disciplines has investigated the effects of using these animations on student learning outcomes and has reported conflicting results. We propose that the theory of cognitive fit in information systems could reconcile these conflicting findings and offer some insight into how these animations might be used most beneficially. We conduct laboratory‐based experiments to test our ideas. Our findings indicate that these representations are superior to text‐based representations and reduce students' cognitive load only in learning tasks where animations have a good cognitive fit. We discuss the implications of our findings for the use of animations and other external representations in the classroom and for future research on the role of Technology Mediated Learning.     

Effectiveness of three‐dimensional digital animation in teaching human anatomy in an authentic classroom context

Three‐dimensional (3D) digital animations were used to teach the human musculoskeletal system to first year kinesiology students. The purpose of this study was to assess the effectiveness of this method by comparing two groups from two different academic years during two of their official required anatomy examinations (trunk and upper limb assessments). During the upper limb section, the teacher used two‐dimensional (2D) drawings embedded into PowerPoint^® slides and 3D digital animations for the first group (2D group) and the second (3D group), respectively. The same 3D digital animations were used for both groups during the trunk section. The only difference between the two was the multimedia used to present the information during the upper limb section. The 2D group surprisingly outperformed the 3D group on the trunk assessment. On the upper limb assessment no difference in the scores on the overall anatomy examination was found. However, the 3D group outperformed the 2D group in questions requiring spatial ability. Data supported that 3D digital animations were effective instructional multimedia material tools in teaching human anatomy especially in recalling anatomical knowledge requiring spatial ability. The importance of evaluating the effectiveness of a new instructional material outside laboratory environment (e.g., after a complete semester and on official examinations) was discussed. Anat Sci Educ 7: 430–437. © 2014 American Association of Anatomists.