号码锁的秘密

几十年来,许多人都像《科学美国人》的读者Billy Ellis那样,曾经对日常生活中的一些小事感到纳闷.     

College quality and early adult outcomes

This paper estimates the effects of various college qualities on several early adult outcomes, using panel data from the National Education Longitudinal Study. I compare the results using ordinary least squares with three alternative methods of estimation, including instrumental variables, and the methods used by Dale and Krueger [(2002). Estimating the payoff to attending a more selective college: An application of selection on observables and unobservables. Quarterly Journal of Economics, 117(4), 1491–1528.] and Black and Smith [(2004). How robust is the evidence on the effects of college quality? Evidence from matching. Journal of Econometrics, 121, 99–124.]. I find that college quality does have positive significant effects on most outcomes studied using OLS. While there is some evidence of positive selection bias in the OLS results, the alternative methods rarely produce findings that are significantly different from the OLS estimates. Furthermore, alternative methods have their own limitations, which are discussed. Across methods of estimation, there is solid evidence of positive effects of college quality on college graduation and household income, and weaker evidence of effects on hourly wages.     

One World,One Dream

地震发生了,我们该怎么办?本文Mark为我们讲述了他的祖国——美国对全民防震意识的教育及在技术上所采取的预防性措施,这对我们应该是一个很好的借鉴。当然,地震来临时,政府也应该调集各种有效力量积极行动起来,对受灾群众迅速进行救助,这是一个人性化的政府应该具备的功能,也恰好是中国政府在5?12大地震中所展现出来的让世界人民刮目相看的风采。     

Age and Sex Differences in Performance in an 11‐plus Selective Examination

The aim of the study was to investigate age and sex differences in performance in an 11‐plus selective examination. The sample was made up of 3460 pupils who were born in 1981 and who had sat the examination for the first time. Results based on a data set consisting of raw scores in Maltese, English, mathematics, social studies and religious knowledge showed a strong and consistent age effect in all five attainment measures: performance decreased with age from the ‘oldest’ pupils to the youngest’. In regard to sex differences, girls outperformed boys in Maltese, English and religion, with differences being most marked in the two languages. The performance of the two sexes in mathematics and social studies was very similar, with the boys’ performance being slightly, but not significantly, better. These age and sex effects were also evident in the proportions of pupils who passed or failed the examination. Older pupils tended to be more successful than younger pupils, and girls were more likely to pass the examination than boys.     

Introducing engineering into American secondary education

Media reports indicate the decline of the technological literacy of American youth, especially that students in other countries are better prepared in science and mathematics. Our active-learning program, which consists of numerous hands-on experiments, introduces engineering applications into science and math programs, that will demonstrate to students the usefulness of the theory that they currently do not see as useful. The program, when fully developed, will make optimum use of technology, especially computers and videotapes. The hands-on experiments allow students to discover fundamental principles through data analysis and then use the principles to synthesize a solution to a technological problem. This discovery-based education will help school systems better meet performance standards such as those in the Maryland School Performance Plan. The experimental approach to science education is especially important in a technology-oriented economy where children use the new technologies without understanding the principles on which they are based.     

Capitalizing on advances in mathematics and k-12 mathematics education in undergraduate mathematics: An inquiry-oriented approach to differential equations

This paper provides an overview of the Inquiry-Oriented Differential Equations (IO-DE) project and reports on the main results of a study that compared students’ beliefs, skills, and understandings in IO-DE classes to more conventional approaches. The IO-DE project capitalizes on advances within mathematics and mathematics education, including the instructional design theory of Realistic Mathematics Education and the social negotiation of meaning. The main results of the comparison study found no significant difference between project students and comparison students on an assessment of routine skills and a significant difference in favor of project students on an assessment of conceptual understanding. Given these encouraging results, the theoretical underpinnings of the innovative approach may be useful more broadly for undergraduate mathematics education reform.     

A bit of both science and economics: a non-traditional STEM identity narrative

Black males, as one non-dominant population, remain underrepresented and less successful in science, technology, engineering, and mathematics (STEM). Researchers focused on non-dominant populations are advised against generalizations and to examine cultural intersections (i.e. race, ethnicity, gender, and more) and also to explore cases of success, in addition to cases of under-achievement and underrepresentation. This study has focused on one African American male, Randy, who expressed high-achieving STEM career goals in computer science and engineering. Furthermore, recognizing that culture and identity development underlie STEM engagement and persistence, this long-term case study focused on how Randy developed a STEM identity during the course of the study and the implications of that process for his STEM career exploration. Étienne Wenger’s (1999) communities-of-practice (CoP) was employed as a theoretical framework and, in doing so, (1) the informal STEM program in which Randy participated was characterized as a STEM-for-social-justice CoP and (2) Randy participated in ways that consistently utilized an “economics” lens from beyond the boundaries of the CoP. In doing so, Randy functioned as a broker within the CoP and developed a non-traditional STEM identity-in-practice which integrated STEM, “economics”, and community engagement. Randy’s STEM identity-in-practice is discussed in terms of the contextual factors that support scientific identity development (Hazari et al. in J Res Sci Teach 47:978–1003, 2010), the importance of recognizing and supporting the development of holistic and non-traditional STEM identities, especially for diverse populations in STEM, and the implications of this new understanding of Randy’s STEM identity for his long-term STEM career exploration.     

An Islamic concept of education

The paper begins by exploring the problematic nature of philosophy in Islam. The second section examines the resources that are available for a systematic exploration of the principles of Islamic education. The third section discusses three dimensions of education in Islam, one focusing on individual development, one on social and moral education and one on the acquisition of knowledge. The paper concludes with a brief discussion of differences between Islamic and liberal ways of understanding education and of the possibility of future dialogue with western philosophies.