Reasoning strategies used by students to solve stoichiometry problems and its relationship to alternative conceptions,prior knowledge,and cognitive variables

Achievement in science depends on a series of factors that characterize the cognitive abilities of the students and the complex interactions between these factors and the environment that intervenes in the formation of students' background. The objective of this study is to: a) investigate reasoning strategies students use in solving stoichiometric problems; b) explore the relation between these strategies and alternative conceptions, prior knowledge and cognitive variables; and c) interpret the results within an epistemological framework. Results obtained show how stoichiometric relations produce conflicting situations for students, leading to conceptual misunderstanding of concepts, such as mass, atoms and moles. The wide variety of strategies used by students attest to the presence of competing and conflicting frameworks (progressive transitions, cf. Lakatos, 1970), leading to greater conceptual understanding. It is concluded that the methodology developed in this study (based on a series of closely related probing questions, generally requiring no calculations, that elicit student conceptual understanding to varying degrees within an intact classroom context) was influential in improving student performance. This improvement in performance, however, does not necessarily affect students' hard core of beliefs.     

运用数学工具解决化学问题

“将化学问题抽象为数学问题,利用数学工具,通过计算和推理(结合化学知识),解决化学问题。”是培养思维能力的重要途径。化学计算事实上是以化学知识为载体,运用所掌握的数学方法,通过分析化学变量之间关系,建立一定数学模型,从而解决化学问题。中学化学中常用到的数学工具有:1　利用数列极限知识计算同系列物质的通式以及原子个数比(或质量分数)的极值例1:在沥青中存在下面一系列有机物:　　……(1)从萘开始这一系列有机物中第25种化合物的分子式是什么?(2)该系列有机物中碳元素的质量分数最大值。解:先写出上述有机物分子式:Ｃ10Ｈ8、Ｃ16…     

浅谈运用化学学科思想方法解决问题

1 运用联系思想解决问题 联系思想主要体现为结构决定性质,性质反映结构;性质决定用途,性质影响制法,用途(制法)反映性质.     

如何用极值法解化学题

极值法是在分析混合物组成时,由于题给条件不充分,采用极限假设的形式讨论未知量的范围,找出两个确定的极值点,再结合题给条件求出结果。该方法的特点是简单明了、快捷,但关键在于找准极值点。现根据自己的教学体会谈谈自己的一些教法。     

Teaching students with LD to use diagrams to solve mathematical word problems

This study examined the effectiveness of instruction focused on teaching students with learning disabilities (LD) to solve 1- and 2-step word problems of varying types. Three students with LD in Grade 8 participated in the study. During the treatment, students received instruction in diagram generation and a strategy that incorporates diagrams as a part of the procedure to solve word problems. The results indicated that all students improved in the number of diagrams they used and in their ability to generate diagrams. Their word problem solving performance increased. Moreover, the students generated and used diagrams to solve other types of problems. Overall, the students were very satisfied with the instruction and would continue to use the diagrams and the strategy to solve word problems in other classroom settings.     

用计算机解决化学教学中的疑难问题一例

介绍了用Matlab软件解决一个化学疑难问题的过程,并引出一些对习题、教学、软件应用等方面的思考。     

Cognitive skills used to solve mathematical word problems and numerical operations: a study of 6- to 7-year-old children

This study investigates the relationship between skills that underpin mathematical word problems and those that underpin numerical operations, such as addition, subtraction, division and multiplication. Sixty children aged 6–7 years were tested on measures of mathematical ability, reading accuracy, reading comprehension, verbal intelligence and phonological awareness, using a mix of standardised and experimenter-designed tests. The experimental hypothesis was that mathematical word problems will call upon cognitive skills that are different and additional to those required by numerical operations, in particular verbal ability and reading comprehension, while phonological awareness and reading accuracy will be associated with both types of mathematical problems. The hypothesis is partly affirmed and partly rejected. Reading comprehension was found to predict performance on mathematical word problems and not numerical operations, and phonological awareness was found to predict performance on both types of mathematics. However, the predictive value of verbal ability and reading accuracy was found to be non-significant.     

How do college students solve proportion problems?

Problems which could be solved using proportional reasoning were administered nationwide by college faculty to their own science classes during a three year period. The reasoning of more than 8000 students covering three sections of the country was classified as concrete, transitional, or formal using Piagetian categories. Data from the West closely replicated that from the Midwest on similar metric conversion tasks. Student performance changed noticeably with a different problem format. The percentages of students using a ratio formula, ratio attempt, or intuitive methods of solution held approximately constant over time, task, and section of the country. The data shows the use of additive and conversion methods of solution depends upon the problem presentation.     

浅谈如何培养初中学生利用概念解决问题的能力

义务教育物理课程标准提出要培养学生分析、解决物理问题的良好习惯。初中物理教学在传授物理知识的同时,应该培养学生利用概念、规律解决问题的良好思维习惯,才能达到义务教育物理课程标准提出的总目标。     

浅谈解决中职生心理障碍教学策略

关注中职生心理健康已成为教育工作者不可回避的重要议题。我们应加强对中职生心理障碍的成因分析,调动社会、家庭、学校的力量,共同寻求这一课题的解决措施,帮助中职生顺利成才。     

Using model-based scaffolds to support students solving context-based chemistry problems

ABSTRACT

Context-based learning aims to make learning more meaningful by raising meaningful problems. However, these types of problems often require reflection and thinking processes that are more complex and thus more difficult for students, putting high demands on students’ problem-solving capabilities. In this paper, students’ approaches when solving context-based chemistry problems and effects of systematic scaffolds are analysed based on the Model of Hierarchical Complexity. Most answers were initially assigned to the lowest level of the model; higher levels were reached without scaffolds only by few students and by most students with scaffolds. The results are discussed with regard to practical implications in terms of how teachers could make use of context-based tasks and aligned scaffolds to help students in this activity.     

求解开放性化学题的六种策略

1 准确回忆,逐一列举 这一类是指教材中研究的问题,在教材中可能集中在一起,也可能分散在不同的章节,有的有明确的说明,有的是以后逐步出现的,但通过归纳总结可形成完整的体系.求解时,只要准确回忆、逐一列举即可.     

Effect of goal setting on the strategies used to solve a block design task

In this experiment we studied the effect of goal setting on the strategies used to perform a block design task called SAMUEL. SAMUEL can measure many indicators, which are then combined to determine the strategies used by participants when solving SAMUEL problems. Two experimental groups were created: one group was given an explicit, difficult goal and the other was not given a goal. The two groups were comparable in their average visual–spatial ability. The results indicated no goal effect on the strategies, defined in terms of the combined indicators. However, the goal did have an effect on some of the indicators taken alone (total problem-solving time, total viewing time, and model-viewing frequency) but this was true only for subjects with a low cognitive ability. These findings demonstrate that setting a goal can have an effect on some strategy indexes used to assess performance on a visual-intelligence design task. This research has implications for defining intelligence-test instructions and educational requirements in school.     

六步解题法

现在高考中常出现含有大量信息的物理考题,这些题目分值一般较高.对于这样的题目,本人认为如采用下面所述的六步解题法去解题,会收到一定效果.六步解题法重在研究做题方法,步骤如下:     

运用数学方法解决化学问题

化学计算是中学化学中的一个重要内容，将化学问题抽象成数学问题，应用数学方法求解，可有效提高学生的思维能力，使解题过程简便、清晰，提高解题速度和正确率。     

巧用函数单调性解题

函数的单调性是函数的重要性质之一 ,平时的教学中我们对于证明函数的单调性 ,求函数的单调区间比较熟悉 ,但对于利用函数的单调性巧妙解题 ,却知之不多。本文归纳介绍它的一些应用 ,供参考。1　求值域例 1　求函数 ｙ=3 ｘ 2 -ｘ -7的值域。解　 ｙ=3 9ｘ 2 ｘ -7,∵ｘ 2 ｘ -7在 [7, ∞ )上单调增 ,∴ ｙ在 [7, ∞ )上单调减 ,∵ｘ≥ 7,∴ 0 <ｆ(ｘ)≤ｆ( 7) =33 ,故 ｙ∈ ( 0 ,33 ]。例 2　求函数 ｙ=ｘ 1ｘ 3 3的值域。解　 ｙ=ｘ 3 1ｘ 3=[ｘ 3-1ｘ 3]2 2 ,∵在 [0 , ∞ )上 ,ｘ 3≥ 3,∴ｘ 3>1ｘ 3,又ｘ 3-1ｘ 3在 […     

数学解题中的辩证策略

数学解题是数学教学和学习中的重要活动 ,把握解题策略远远要胜于一招一式的解题方法。而辩证法如同在指导其它学科一样 ,在指导数学解题策略方面也有着重要的作用。1　正难则反策略对于有些数学题 ,从正面入手往往比较难或较繁 ,如果改变解题策略 ,从反面去思考 ,则反而容易。例 1　在三个方程ｘ2 ｍｘ 4 =0 ,ｘ2 2ｘ -2ｍ =0 ,ｘ2 (ｍ 1 )ｘ -(ｍ2 -1 ) =0中 ,要使其中至少有一个方程有实根 ,问ｍ应当取怎样的实数值。分析　本题若从正面去思考 ,要分三种情况 :①三个方程中有一个方程有实根 ,②三个方程中有二个有实根 ,③三个方程…