对一道创新思维题的探讨

贵刊2001年第9期上刊登了一篇题为《谈物理教师的创造性思维》的文章。我们对文中例3的科学性提出质疑,为便于讨论,现将本例及作者的分析摘录如下: [题目]甲球以初速度沿着光滑的水平面从A运动到B,乙球以同样的水平速度υ0沿光滑曲面从A运动到B,A、B的水平距离相同,如图,比较小球从A到B所用的时间t甲和t乙。 [分析]这道题讲它“活”,活在能考查学生能否灵活运用机械能守恒定律和运动的独立     

《简易逻辑中的常见错误》中的错误

《中学数学教学参考》2 0 0 3年第 5期《简易逻辑中的常见错误》(以下简称为《错误》)一文中出现了几处错误 ,本文剖析一下这几处错误 .《错误》一文中的例 7给出命题 p :“若x2 + y2 =0 ,则x ,y全为 0” ,认为命题 p的“非”是┐ p :“若x2 +y2 =0 ,则x ,y不全为 0” .《错误》一文中的例 8给出命题 p :“若x =2或x= -1 ,则x2 -x -2 =0” ,认为它的“非”是┐ p :“若x=2或x =-1 ,则x2 -x -2≠ 0” .这两个例子犯了相同的错误 .错误就是把“若A则非B”当成了“若A则B”的否定命题 .《错误》一文在例 8的后面有一段小结 ,其中有一句是“否…     

哪种电荷在移动?

初中物理《电路》一章第三节《电流》中有这样一个实验:取两个相同的验电器A和B,使A带电,B不带电(图甲)用金属棒把A和B连接起来,可以看到A的金属箔张开的角度减小,B的金属箔张开,最后两个验电器金属箔张开的角度相同(图乙),这表明验电器B     

对新教材“电流”一节导语的商榷

人教版 ( 2 0 0 1年 3月第一版 )九年义务教育三年制初级中学教科书《物理》第二册第 4 7面“电流”一节中的导语这样表述 :“取两个相同的验电器 A和 B,使 A带电 ,B不带电 (图甲 ) .用金属棒把 A和 B连接起来 ,可以看到 A的金属箔张开的角度减小 ,B的金属箔张开 ,最后两个验电器的金属箔张开的角度相同 (图乙 ) ,这表明验电器 B也带了电 ,有电荷通过金属棒从 A流到 B,也就是说 ,用金属棒把 A和B连接起来时 ,金属棒上有了电流 ,但这种电流是短暂的 ,不是持续的 .”图甲图乙笔者认为“有电流通过金属棒从 A流到B”,这种表述是不准确的 …     

有机反应类型 有机推断与合成

考点一、侧重于有机物性质和反应现象的推断【例 1】　A、B都是芳香族化合物 ,1molA水解得到 1molB和 1mol醋酸 ,A、B的分子量都不超过 2 0 0 ,完全燃烧都只生成CO2 和H2 O ,且B分子中碳氢元素总质量分数为 6 5 .2 % ,A溶液具有酸性 ,不能使FeCl3 溶液显色 .(1)A、B分子量之差为　　　　 ;(2 ) 1个B分子中应该有　　　个氧原子 ;(3)A的分子式是　　　　 ;(4)B可能的三种结构简式是　　　　　　　 .分析 :由A +H2 OCH3 COOH +B ,知A +18=6 0 +B ,所以A、B相对分子质量相差 6 0 - 18=4 2 .B的相对分子质量不超过 2 0 0 - 4 2 =1…     

《绿野仙踪》中的AABB式词——兼谈AABB式词在明清时期的发展变化

按照A、B的语法功能将《绿野仙踪》中的AABB式词进行分类,并将其与《金瓶梅》中的AABB式词作比较,可以发现,到《绿野仙踪》时代,AABB式词结构组合中A和B的语义限制已被突破;由语法功能相同或相近的A、B组合成的AABB式词能产性最高;与《金瓶梅》相比,《绿野仙踪》中AABB式词的结构方式和语法功能更为灵活、多样。     

Урóк 7

一、听对话 1— 5,选出最佳选项。1 .КогдШрадетвВолгогрд ?A .Вовтрник.　　B .Всрду.　　C .Вчетврг.2 .Когдотхдитпезд《Пекн Москв》 ?A .В 6.B .В 6 3 0 .C .В 7 3 0 .3 .КогдОлгиРяпойдтвкин?A .Вчером . B .Сегдня.C .Звтра.4.КтоприхалвкомандирвкувМоскв ?A .МихалСергевич.　　B .АннаАлексндровна.C…     

Урк 4

一、听对话 1— 5,选出最佳选项。1 .Чтоонвчерсмотрл ?A .Фильм《Тыуменодн》 .　　B .Фильм《Гроз》 .C .Балт《Лебедноезеро》 .2 .Когдотхдитпезд ?A .В 2 0часв.　　B .В 1 2часв.　　C .В 2час.3.КакНнасебчвствуетсейчс?A .Плхо.　　B .Неченьхорош.　　C .Ужхорош.4.СклькодетйуИрныВкторовныиИвнаИ…     

外国教材中的数学题目选编(中年级用)

1.破译算式。(不同字母代表0、1、2、3、4……9中不同的数字)①A B×A B CA B解:两个相同的两位数的乘积是三位数,则此数必在10与33之间,又个位数都是 B,所以 B只可能是 0、1、5或 6。当 A=1时,B=0、1、5、6时算式都不成立;当 A=2时,B=0、1、6时算式都不成立,但B=5时,25×25=625符合要求;当A=3时,B=0、1、5、6时,算式也都不成立。 25     

密度例题精析

例1如图a所示的是甲、乙两种物质的质量——体积关系图像,由图像可知m/g乙甲V/cm3a b cm/g乙甲V/cm3ABm甲m乙V0m/g乙甲V/cm3m0CDV乙V甲A.ρ甲>ρ乙B.ρ甲=ρ乙C.ρ甲<ρ乙D.无法比较ρ甲与ρ乙的大小精析此类型题一般有两种解法,根据公式ρ=mV可以取相同质量的不同物质,比较体积,体积大的密度小,体积小的密度大;也可以取相同体积的不同物质,比较质量,质量大的密度大,质量小的密度小.解法1:在图b的横轴上任取一点V0,由V0作横轴的垂线,交甲、乙两图像于A、B两点,分别由A,B两点作纵轴的垂线,交纵轴于m甲、m乙,由图像可知m甲相似文献   

Having a Whale of a Time

A classroom practical exercise exploring the reliability of a basic capture‐mark‐recapture method of population estimation is described using great whale conservation as a starting point. Various teaching resources are made available.     

对公推直选乡镇长与乡镇党委书记的比较

公推直选乡镇长与乡镇党委书记出现的时间、发展现状与趋势、制度依据、选举成本,以及乡镇长与乡镇党委书记在乡镇政权中的作用有明显的不同。在我们看来,直接选举乡镇党委书记,发展的空间更广阔,对乡镇民主建设与乡镇政府职能转型所起的作用更大。     

一道联赛题的推广

题1 已知实数a、b、c、d互不相等，且n＋1/b=b＋1/c=c＋1/d=d＋1/a=x．     

关于循环矩阵求逆的一种算法

给出了利用多项式的欧几里德算法判断循环矩阵的可逆性和求逆的方法     

向量与数的乘法

Vectors may also be multiplied by a number. The productof the vector a by the number λ is defined as the vector a λ=λa, the absolute value of which is obtained by multiplying theabsolute value of the vector a by the absolute value of thenumber λ, i. e. |λa|=|λ||a|, the direction coinciding withthe direction of the vector a or being in the opposite sensedepending on whether λ>0 or λ<0. If λ=0 or a=0, then λ a     

三角形的一个性质的推广

本对[1]给出的三角形的一个性质进行推广．     

向量与数的乘法

（参考译文）。 向量也可和数做乘法．向量a与数字A的乘积定义为向量aλ—λa,它的绝对值是向量a的绝对值和数字A的绝对值的乘积,     

Paving a clear path in a thick forest: a conceptual analysis of a metacognitive component

The concept of metacognition refers to one’s knowledge and control of one’s own cognitive system. However, despite being widely used, this concept is confusing because of several reasons. First, sometimes it is not at all clear what is cognitive and what is metacognitive. Second, researchers often use the same term, namely, “metacognition” even when they refer to very different aspects of this complex concept. Alternatively, researchers may use different terms to indicate the same metacognitive elements. Another foggy matter is the interrelationships among the various components of metacognition discussed in the literature. This conceptual confusion regarding the concept of metacognition and its sub-components calls for in-depth theoretical and conceptual clarifications. The goal of this article is to portray a detailed example of a conceptual analysis of meta-strategic knowledge (MSK) which is one specific component of metacognition. This specific example is used to draw a general model for conceptual analyses of additional metacognitive components. The approach suggested here is to begin with a clear definition of the target sub component of metacognition, followed by a systematic examination of this sub component according to several dimensions that are relevant to metacognition in general and to that sub component in particular. The examination should include an analysis of how the details of the definition of the target sub-component refer to: (a) general theoretical metacognitive issues raised by prominent scholars; (b) definitions formulated and issues raised by other researchers who have investigated the same (or a similar) sub-component and, (c) empirical findings pertaining to that sub-component. Finally, it should be noted that since metacognition is a relational rather than a definite concept it is important to situate the context within which the conceptual analysis takes place.     

Rate of a maintained operant as a function of temporal position within a session

McSweeney and her colleagues (e.g., McSweeney, Hatfield, & Allen, 1990) have demonstrated reliable, large magnitude rate changes in maintained operants within daily sessions under a wide variety of reinforcement schedules. The present paper examined the role of schedule of reinforcement, reinforcement rate, and total amount of food access in determining those within-session rate changes. When median rates across birds were considered, all procedures resulted in a brief period of an increasing rate, followed by a modest rate loss across the major portion of the session. However, not all individuals exhibited that pattern. When the amount of food access per session was limited by lower reinforcement rates, shorter sessions, or shorter reinforcement durations, the magnitude of the withinsession rate change was reduced from that occurring without those constraints. Additionally, under the conditions that produced strong within-session rate changes, the magnitude of the within-session rate loss was correlated with the bird’s body weight. These effects are consistent with what is typically labeledsatiation.     

Developing a professional vision of classroom practices of a mathematics teacher: views from a researcher and a teacher

The term professional vision points to the many nuanced ways professionals see. This paper traces the development of a professional vision of a researcher and a teacher looking at classroom practices. The researcher’s interest was to capture and study notable aspects of the teacher’s practice. Through a coding scheme, disparate classroom events were organized and analyzed to yield a researcher’s professional vision of the teacher’s practices. For the teacher, through reviewing the video records of his own classroom practices, his professional vision provided a basis for him to reflect and develop professionally. Leveraging on the work of the researcher, he initiated and transformed his own practices. Their collaboration yielded a mutually informed development of professional vision of classroom practices. In juxtaposing the two developments, the researcher and the teacher’s views can be contrasted, their distinctive interests highlighted and common grounds explored. Some implications for developing professional vision are drawn, and it is in the common grounds of the teacher’s professional development and seeing with a goal of enhancing of student learning that hold some promise of a mutual interest in developing a professional vision of classroom practices.