Burning a Candle in a Vessel, a Simple Experiment with a Long History

The experiment in which a candle is burned inside an inverted vessel partially immersed in water has a history of more than 2,200 years, but even nowadays it is common that students and teachers relate the change in volume of the enclosed air to its oxygen content. Contrary to what many people think, Lavoisier concluded that any change in volume in this experiment is negligible; moreover, the explanation relating oxygen consumption in the air with its change in volume is known to be wrong. In this work we briefly review the history behind the candle experiment and its relationship with some typical erroneous explanations. One of the key factors behind Lavoisier’s success was the use of experiments carefully designed to test different hypotheses. Following these steps, we performed several closed volume experiments where the candle wick was replaced by a capillary stainless steel cylinder supported and heated by a nichrome filament connected to an external power supply. Our recorded experiments are displayed as web pages, designed with the purpose that the reader can easily visualize and analyze modern versions of Lavoisier’s experiments. These experiments clearly show an initial phase of complete combustion, followed by a phase of incomplete combustion with elemental carbon or soot rising to the top of the vessel, and a final phase where the hot artificial wick only evaporates a white steam of wax that cannot ignite because no oxygen is left in the closed atmosphere. After either a complete or incomplete combustion of the oxygen, our experiments show that the final gas volume is nearly equal to the initial air volume.     

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.     

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。     

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.     

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.     

影响物流中心选址的因素及一种选址方法

文章论述了影响物流中心选址的七大因素,建议采用模糊评判的方法,该方法克服了传统选址方法的片面性、局限性和计算的复杂性,可对多种可供选择的方案做出明确的排序,使选址问题变得更加合理、科学与全面,更加反映客观实际.     

Introducing a mentor into a children's composition project: Reflections on a process

This article reports on a case study where a professional musician was assigned to a primary school as mentor in a project where 14 primary-aged children, with their teacher's direction, were involved in the composition of a piece of music that would act as prologue to the school's major production. The researchers were interested in aspects of the composition project that appeared to develop student's compositional skills and motivation and how the mentor might exercise his role in the composition project alongside the teacher, who was the school's music specialist. A range of data was analyzed: classroom observations, emails, questionnaires, and one-on-one and focus-group interviews. Findings suggested that the involvement of the mentor was well received by the pupils and that the mentor and teacher complemented one another in their enactment of both pedagogical and compositional roles. Students enjoyed a high sense of success in the production of their composition. Student learning were highly variable and a range of activities and processes was identified by students as contributing to their learning.     

科学定位，凸显特色，创建品牌——关于办好地方本科院校学报的思考

地方本科院校学报具有学术窗口、学院名片、学人摇篮、服务平台等功能。对地方本科院校学报进行科学的定位,首先要结合学校定位,其次要着眼地域定位,寻求错位发展,尤其要处理好学术性与应用性的关系、内向性与开放性的关系、科学性与人文性的关系。为提高学报的办刊水平与质量,办出特色,地方本科院校学报要坚持走特色化与品牌化道路,在办刊质量、学术品位、特色栏目创设、编辑素质、装帧设计上下功夫。     

建设好实验室是一个挑战

实验室的建设应与学校的定位相匹配,对于大规模的综合大学,实验室建设是一个挑战,应分层次建设实验室,给教师、学生提供一个像家一样的实验环境。提出实验室的使用与管理分开的管理体制,实验室管理实行实验业务以块为主,管理以条为主的条块结合的机制。并指出实验室应有一个专门的管理机构。     

Just a Body in a Wheelchair

This article has no direct link with academics, children, students or those who teach: I severed almost all such connections several years ago. It describes the rewards and challenges of leading a reminiscence group of elderly people, all of whom suffer some level of memory loss and/or severe physical disability; most are wheelchair-bound. It contains examples of their autobiographical talk which I recorded separately from group meetings and transcribed, exclusively for the satisfaction of each individual concerned. Ours is not a society which cherishes its aged members. What becomes of their identity? Who are they now? They are, of course, people – as interesting as those in our classrooms. They too need to know their own worth.     

Dynamic response of a beam on a Pasternak foundation and under a moving load

The dynamic response of an infinite beam placed on a Pasternak foundation when the system was subjected to a moving load was investigated. We used the double Fourier transform and its inversion to solve the formulations of the problem. A closed form analytic solution of the beam was obtained by the theorem of residues. We selected a numerical example to illustrate the dynamic response of the beam on Pasternak and Winkler foundations, respectively. We discuss the effect of the moving load velocity on the dynamic displacement response of the beam. The maximum deflection of the beam increases slightly with increased load velocity but increases significantly with reduced shear modulus of subgrade at a given velocity. The maximum deflection of a beam resting on a Pasternak foundation is much smaller than that of a beam on a Winkler foundation.     

On embedding a semigroup in a group

In this article, we explain the idea of Rees [1] to utilize the inverses of partial one-one functions on a cancellative monoid S to embed S into a group.     

Adding a Data Point to a Scatterplot

Students who have been taught regression properly are certainly familiar with the dangers and curiosities to which the regression analysis leads when only two data points are available. However, one may ask whether students are familiar with the effects of adding a third observation into this data set. The purpose of this article is to illustrate some unexpected phenomena related to this situation using a specific map technique.     

The internet as a tool to learn a second language in a technical environment

Second language acquisition is a hard task for teachers, since to achieve the motivation from students to practice a language simulating a real context is very difficult. On the one hand, students are often influenced by their mother tongue and more when they are practising a second language with a partner from the same nationality. On the other, technology is part of our lives and teachers should use all the tools in order to motivate students to learn any topic. So, if we integrate technology in the methodology we use when teaching a second language and students can practise with international partners, the results can be surprising. Chats, scanning texts, games, filling forms, etc. are just some of the activities our students can do in order to improve their command of a second language and also these activities can be used by content teachers in order to complement content learning. In the present paper, we provide some examples of activities designed by collaborating with content teachers based on websites, and then we analyse the effect they produced on students. We contrast the methodology used to propose tasks based on websites and those based on texts, and finally, evaluate their effect on the motivation of students.     

Exemplifying definitions: a case of a square

In this study we utilize the notion of learner-generated examples, suggesting that examples generated by students mirror their understanding of particular mathematical concepts. In particular, we explore examples generated by a group of prospective secondary school teachers for a definition of a square. Our framework for analysis includes the categories of accessibility and correctness, richness, and generality. Results shed light on participants’ understanding of what a mathematical definition should entail and, moreover, contrast their pedagogical preferences with mathematical considerations.     

Lifelong learning: a policy concept with a long past but a short history

This article examines the continuities and discontinuities in the international problematisation of education across the lifespan as an education policy, currently conceptualised as lifelong learning. Through the critical examination of international organisations’ policy documents, this paper demonstrates that while on the one hand there is a pattern in the way the problematisaton has been carried out (the continuities), on the other hand the translation of the problematisaton into policy has been punctuated by major discontinuities. Lifelong learning as a policy concept has introduced strong discontinuities that have ensured its acceptance worldwide: a policy with a small degree of political operationalisation that simultaneous discursively combines different political orientations.     

公历星期推算图

星期纪日是以 7为周期的纪日方法。每日的星期号数与公历日期并无规律 ,应用诺模图原理绘制的星期推算图 ,无需作任何计算 ,根据公历年月日即可方便快捷地求出当日的星期号数     

The motion of a charged particle in a magnetic field produced by a column current

To determine the motion of a charged particle in a magnetic field produced by a current flowing along a long column conductor, the equation of the motion was established on the basis of Lorentz force. Qualitative analysis and quantitative solutions demonstrated that the motion contains nonlinear oscillation. The oscillation can be treated as the perturbation of the helical motion, Which the particle undergoes in a special condition. The general motion is superposition of two helixes, one as an axis spiraled by another. It is proven that the oscillation is stable.     

返回指针与引用的函数

在C/C++中,函数是编程的基本单位。函数的返回值可以是任何合法的数据类型,但是,当函数的返回值是指针或引用类型时,有其特殊性。主要讨论返回值是指针或引用的函数的几种情形。     

返回指针与引用的函数

在C／C＋＋中,函数是编程的基本单位。函数的返回值可以是任何合法的数据类型,但是,当函数的返回值是指针或引用类型时,有其特殊性。主要讨论返回值是指针或引用的函数的几种情形。