A content analysis of the presentation of the mole concept in chemistry textbooks

The goal of this study was to examine the means used by textbook authors to introduce, define, and explain the mole concept in high school and introductory college chemistry textbooks. The analysis was framed by four questions:

• 1 How is the mole defined?
• 2 What concepts about the atom are introduced prior to the mole?
• 3 Is Avogadro's constant presented as an experimentally determined value?
• 4 What is the context for introducing the mole?

Twenty-nine high school and introductory college level chemistry texts were examined. After independent reading of appropriate sections of each text, discussion of differences, second or third readings of texts, and subsequent discussions, both authors reach 100% agreement concerning the results. Major conclusions were

• 1 Two ways of defining the mole dominate the texts. One way defines the mole as Avogadro's number (6.02 × 10²³) particles; the other method defines the mole in terms of carbon-12.
• 2 All texts that present a definition in terms of C-12 introduce and define concepts about the atom prior to introducing the mole.
• 3 Most texts at all levels point out that the value 6.02 × 10²³ is an experimentally determined quantity.
• 4 Nearly all texts discuss the mole in relation to die problem of finding a way to count particles that are too small to be directly weighed. Most texts also use a familiar counting unit, such as the dozen, to introduce the mole by analogy.

Four issues were discussed: (a) the defining attributes of the mole concept itself and the cognitive requirements for comprehending the two most frequently used definitions; (b) the connection between the definition of the mole presented in the text and the concepts about atoms that are introduced before the mole concept is developed; (c) the experimental nature of Avogadro's number; and (d) the context or setting for developing the mole concept.     

The Impact of an SES-Based Model on a College's Undergraduate Admissions Outcomes

In Grutter vs. Bollinger, the U.S. Supreme Court ruled that the use of race as one factor, among many in admissions decisions is constitutional. It is not known, however, whether future legal opinions will continue to uphold the use of affirmative action policies. Some have argued that class-based preferences can achieve many of the same goals as in affirmative action while being more likely to withstand legal challenges. To date, no empirical studies have been conducted on the potential impact of a class-based admissions policy if implemented at an undergraduate institution. This paper reports on a study at a selective public college and compares a number of outcomes under three admissions models: the original admissions decisions, a purely academic model, and an socio-economic status (SES)-based model. The findings showed that use of the SES-based model would have led to a more academically qualified class than in the original admitted class while maintaining substantially greater student diversity that was found under the academic model. An admissions policy based on preferences for socio-economically disadvantaged applicants appears to hold promise for other colleges and universities with similar institutional and applicant characteristics. The ideas and research design reported in this paper are based on the doctoral dissertation study of the second author, Undergraduate Admissions Models Incorporating Socioeconomic Factors (Johnson, 2000).     

死神与诗人

这首诗出自于英国 17 世纪伟大诗人约翰·邓恩 ( 1572￣1631) 的《神圣十四行诗》。约翰·邓恩系玄学派代表诗人, 其诗歌通常给人留下一种舞台戏剧的印象。诗的开篇大都是以语言通俗、言辞激烈的戏剧性对话或争论的形式出现, 渲染了戏剧的舞台气氛, 在读者中产生戏剧悬念, 既而推动诗歌主题步步升华。诗人独具匠心, 在诗歌中巧妙运用戏剧表现手法, 通过使用一系列注重智力, 意象华丽且富含戏剧对比性因素的比喻, 将激情与推理融为一体, 给诗歌注入了新的活力, 向读者传达了奇妙的艺术效果。     

How to decide how to decide

This article attempts to characterize the general problem of selecting methods for decision-making. The traditional rational approach to choice is from economics, which offers expected-value maximization. The task environment of decision method selection, however, does not seem to provide the data necessary for carrying out the expected-value calculations. Our approach uses methods from the field of cognitive science. We develop the notion of domain size in fields such as chess, borrowing the concept of a chunk from human memory. We then develop a heuristic rule for choiceamongmethods. We propose this rule as one of many possible rules.     

A sociocultural perspective on mediated activity in third grade science

This ethnographic study of a third grade classroom examined elementary school science learning as a sociocultural accomplishment. The research focused on how a teacher helped his students acquire psychological tools for learning to think and engage in scientific practices as locally defined. Analyses of classroom discourse examined both how the teacher used mediational strategies to frame disciplinary knowledge in science as well as how students internalized and appropriated ways of knowing in science. The study documented and analyzed how students came to appropriate scientific knowledge as their own in an ongoing manner tied to their identities as student scientists. Implications for sociocultural theory in science education research are discussed. John Reveles is an assistant professor in the Elementary Education Department at California State University, Northridge. He received his Ph.D. from the University of California, Santa Barbara in 2005. Before pursuing his Ph.D., he worked as a bilingual elementary school teacher for 3 years. His research focuses on the development of scientific literacy in elementary school settings; sociocultural influences on students' academic identity; equity of access issues in science education; qualitative and quantitative research methods. Within the Michael D. Eisner College of Education, he teaches elementary science curriculum methods courses, graduate science education seminars, and graduate research courses. Gregory Kelly is a professor of science education at Penn State University. He is a former Peace Corps Volunteer and physics teacher. He received his Ph.D. from Cornell in 1994. His research focuses on classroom discourse, epistemology, and science learning. This work has been supported by grants from Spencer Foundation, National Science Foundation, and the National Academy of Education. He teaches courses concerning the uses of history, philosophy, sociology of science in science teaching and teaching and learning science in secondary schools. He is editor of the journal Science Education. Richard Durán is a Professor in the Gevirtz Graduate School of Education, University of California, Santa Barbara. His research and publications have been in the areas of literacy and assessment of English Language Learners and Latino students. He has also conducted research on after school computer clubs, technology and learning as part of the international UC Links Network. With support from the Kellogg Foundation, he is implementing and investigating community and family-centered intervention programs serving the educational progress of Latino students in the middle and high school grades.     

The nexus between college choice and persistence

Initial student commitments have long been considered an influence on persistence, but the reasons why students choose to attend a college have seldom been considered as dimensions of initial commitments that could influence persistence processes and outcomes. This study used NPSAS-87 to examine the influence of finance-related reasons for choosing a college on persistence decisions. The findings include (1) finance-related choices have direct and indirect influences on whether students persist in college; and (2) market-based, monetary measures of financial aid, tuition costs, housing costs, and other living costs have a substantial direct effect on persistence.