Science Talk: Preservice Teachers Facilitating Science Learning in Diverse Afterschool Environments

The purpose of this study was to assess the impact a community‐based service learning program might have on preservice teachers' science instruction during student teaching. Designed to promote science inquiry, preservice teachers learned how to offer students more opportunities to develop their own ways of thinking through utilization of an afterschool science program that provided them extended opportunities to practice their science teaching skills. Three preservice teachers were followed to examine and evaluate the transfer of this experience to their student teaching classroom. Investigation methods included field observations and semi‐structured, individual interviews. Findings indicate that preservice teachers expanded their ideas of science inquiry instruction to include multiple modes of formative assessment, while also struggling with the desire to give students the correct answer. While the participants' experiences are few in number, the potential of afterschool teaching experience serving as an effective learning experience in preservice teacher preparation is significant. With the constraints of high‐stakes testing, community‐based service learning teaching opportunities for elementary and middle‐school preservice teachers can support both the development and refinement of inquiry instruction skills.     

Behind the Masks: Identifying Students' Competencies for Learning Mathematics and Science in Urban Settings

Three mathematics and science educators reexamine and reflect on their teaching within the context of the American Association for the Advancement of Sciences (AAAS) and National Council of Mathematics' call to make math and science education accessible to all. The paper highlights the importance of teachers reflecting on their teaching practices in order to create opportunities for their students especially those in the urban setting. The educators argue that teachers' reflection on their teaching can cause them to recognize and validate their students' ways of knowing as they identify the students' hidden/concealed abilities that are often masked by their behaviors. The educators discuss their experiences and highlight the lessons that they learned about ways to prepare teachers to successfully teach math and science students in urban settings. Culturally responsive pedagogy and cultural competency are critical skills that teachers need to develop in order to teach all children, especially those in the math and science classroom in the urban setting.     

Logistic回归模型在信用风险分析中的应用

通过运行SPSS,建立L og istic回归信用评价模型(cred it eva luation m odel),用来对中国2000年106家上市公司进行两类模式分类,这两类模式是指按照公司的经营状况分为“差”和“正常”两个小组.对每一家上市公司,考虑其经营状况的4个主要财务指标:每股收益、每股净资产、净资产收益率和每股现金流量.仿真结果表明,L og istic回归信用评价模型对总体106个样本,判别准确率达到99.06%.此外,本文的研究结果还发现,当利用SPSS的D iscrim inan t给出的模型系数建立的线性判别分析模型和利用SPSS的M u ltinom ia lL og istic给出的模型参数建立的L og istic回归模型,L og istic回归模型的判别结果不如线性判别模型.但如果剔除不合格的样本,或是将样本数据规格化,则可以提高L og istic回归模型的分类准确率.     

Sociocultural Factors Influencing Students' Learning in Science and Mathematics: An Analysis of the Perspectives of African American Students

The voices of African American students reveal sociocultural factors that influence their achievement in science and mathematics classes. Using a sociocultural theoretical framework ( Mercer & Covey, 1980 ), this ethnographic study interpreted the perspectives of five African American students as they discussed their learning experiences in science and mathematics classrooms. This framework acknowledges the vulnerability of the educational system to societal influences that inevitably assert cultural values and norms. The students' discussions provided insight into their beliefs about the varied ways in which sociocultural factors impact their learning in science and mathematics classrooms.     

一种估计Logistic模型参数的方法及应用实例

分析了Logistic函数的解析性质,得到了曲线上三个关键点和三个不同的增长阶段,利用差分和最小二乘法,给出了Logistic模型的一种便于使用的参数估计方法．并通过实例,建立Logistic模型对我国城镇居民家庭平均每百户彩色电视机拥有量的增长变化趋势进行了分析和预测．     

Investigating Essential Characteristics of Scientific Practices in Elementary Science Learning Environments: The Practices of Science Observation Protocol (P‐SOP)

Within the field of science education, there remains little agreement as to the definition and characteristics of classroom inquiry. The emerging emphasis on scientific practices in science education reform discourse is underpinned by a need to better articulate the constituent elements of inquiry‐based science. While a small number of observation‐based instruments have been developed to characterize science learning environments, few are explicitly aligned with theoretical constructs articulated by the National Research Council and/or have been substantially field‐tested. We employ a newly developed instrument, the Practices of Science Observation Protocol (P‐SOP), to investigate essential features of inquiry and scientific practices in which early learners engage in elementary classrooms. This research is part of a multiyear professional development program designed to support elementary teachers (K‐5) in a large, urban school district to learn to better engage students in scientific practices. Project teachers video‐recorded enacted science lessons (n = 124) which were used as data. Findings illustrate both essential features of inquiry and scientific practices observed in elementary classrooms, as well as establish the P‐SOP as a valid and reliable observation protocol. These findings have important implications for the design of elementary science learning environments and associated research and development efforts in the field.     

The Effects on Students' Cognitive Achievement When Using the Cooperative Learning Method in Earth Science Classrooms

This study investigated the effects of cooperative learning instruction versus traditional teaching methods on students' earth science achievement in secondary schools. A total of 770 ninth-grade students enrolled in 20 sections of a required earth science course participated in this nonequivalent control group quasi-experiment. The control groups (n= 10) received a traditional approach, while the experimental groups (n= 10) used cooperative strategies. Study results include (a) no significant differences were found between the experimental groups and the control groups when overall achievement (F= 0.13, p > .05), knowledge-level (F= 0.12, p > .05), and comprehension-level (F= 0.34, p > .05) test items were considered; and (b) students who worked cooperatively performed significantly better than students who worked alone on the application-level test items (F= 4.63, p < .05). These findings suggest that cooperative-learning strategies favor students' earth science performance at higher but not lower levels of cognitive domains in the secondary schools.     

学习曲线在成本计划评审应用

论文介绍了计划评审法(PERT)的基本思想,探讨了学习曲线模型在PERT图中的应用,并给出了相应实例.     

Logistic回归模型选择的渐近概率

在许多情况下，我们需要对logistic回归模型中的重要变量进行选择，在本文中，我们对从信息论准则AIC选择出的模型给出了渐近分布和渐近概率。     

Gender Differences in Science Achievement: Differential Effect of Ability,Response Format,and Strands of Learning Outcomes

The purpose of this study was to determine patterns of gender differences in science achievement of fifth graders, taking into account the role of ethnicity, ability, response format, and strands of learning outcomes. The results indicated that the gender differences in science achievement did not depend on ethnicity. However, response format, ability, and strands of learning outcomes had differential effects on student performance. In particular, at the high ability level boys did better than girls on the open-ended format in physical sciences, but there were no gender differences in nature of science, earth and space sciences, and life sciences. There were no gender differences in science achievement for the low and medium ability students. Regardless of gender, the largest achievement gaps between the low, medium, and high ability students were on the open-ended format in physical sciences.     

Integrating Science,Mathematics, and Technology in Middle School Technology‐Rich Environments: A Study of Implementation and Change

The GTECH project, funded through a grant from the GTE Foundation, prepared school teams of science, mathematics and technology teachers and an administrator to set goals for their local schools regarding implementation of electronic technology and integration of content across curricular areas. A variety of teacher‐centered staff development strategies were used to enable participants to achieve local school objectives, model and encourage active learning environments involving technology, develop integrated curriculum and provide training to their peers. GTECH staff provided workshops and summer institutes based on teacher feedback and classroom observations. Data from the Stages of Concerns Questionnaire assisted the staff in designing effective staff development activities. Over the 2‐year period, teacher teams developed and implemented integrated instructional materials and developed skills in using HyperStudio, PowerPoint, telecommunications applications, and instructional resources from the Internet. They also linked instruction to new state and national standards in science, mathematics, and technology. GTECH teachers reported that their students have expanded their knowledge and skill in problem solving, teamwork, technical expertise, and creativity.     

应用RJMCMC方法识别线性模型异常点

传统线性模型异常点识别方法容易发生误判:正常点被归为异常点或者异常点被归为正常点.为解决此类问题,提出了应用逆跳马尔科夫蒙特卡洛方法识别异常点的思想,同时将其应用于实际数据加以检验,识别效果明显好于传统方法.     

基于解释结构模型的学生学习行为投入评价因素研究

学生学习行为投入是教学研究中的热点问题,对改善学习绩效,提升教育质量具有重要意义.通过文献梳理和专家访谈,识别出学生学习行为投入评价影响因素的15个变量,并确定了各因素变量之间的二元关系.在此基础上,采用解释结构模型方法对这些影响因素进行层级建模,得到学生学习行为投入评价影响因素解释结构模型.研究发现:学术拓展、任务独立、寻求挑战、交流讨论、协作学习、克服困难是影响学习行为投入的直接因素,更多的投入、自我检测、积极响应、出勤和参与决策与管理是根本因素,坚持、专注、自我调节和任务管理作为间接因素发挥作用.最后对研究结果进行相关分析,进而为促进学生学习行为投入提供一定的参考.     

A Linear,First-order Shell Model for Transverse Isotropic Material under a Uniform Change of Temperature

A first-order shell model is derived for describing the behaviour of a thin, arbitrarily curved structure made from homogeneous, transverse isotropic material under the influence of a uniform change of temperature. Transverse isotorpy means that the elastic behaviour and the thermal expansion is isotropic in in-plane directions but different in thickness direction. The influence of the different thermal expansion is incorporated by equivalent stress couples and bending moments. Thus, a higher-order approximation in thickness direction is not necessary. However, the so-called ‘second approximation of shell theory’ must be used which deals with more accurate constitutive relations than the standard theory. Further the question is investigated in which cases a stress-free transverse isotropic thermal deformation exists.     

累积logistic回归在后发企业技术能力提升研究中的应用

分析了累积logistic回归模型在后发企业技术能力提升研究中的适用性,并以汽车零部件企业为例进行了实证分析.研究扩展了针对中国的中技术制造业的后发企业技术能力提升的认识,并对后发企业技术能力提升的实证分析方法进行了探讨.研究结论显示:对汽车零部件企业而言,其技术发展模式较封闭,外部知识来源的多寡并不是技术能力提高的重要方式.而内部的研究开发和正式的外部研发合作是提高技术能力的重要来源,企业规模也是影响企业能力提升的重要因素.研究表明该实证分析方法在相关研究中具有可行性.     

Proof in School Mathematics: Insights from Psychological Research into Students' Ability for Deductive Reasoning

There are currently increased efforts to make proof central to school mathematics throughout the grades. Yet, realizing this goal is challenging because it requires that students master several abilities. In this article we focus on one such ability, namely, the ability for deductive reasoning, and we review psychological research to enhance what is currently known in mathematics education research about this ability in the context of proof and to identify important directions for future research. We first offer a conceptualization of proof, which we use to delineate our focus on deductive reasoning. We then review psychological research on the development of students' ability for deductive reasoning to see what can be said about the ages at which students become able to engage in certain forms of deductive reasoning. Finally, we review two psychological theories of deductive reasoning to offer insights into cognitively guided ways to enhance students' ability for deductive reasoning in the context of proof.