They censor,I select

What happens when a bookseller does not want to stock or sell a specific title? Does this act represent a decision to censor a title? Or, perhaps, does it reflect a bookseller's belief that a book would offend customers (the moral or political argument)? In this article the author explores covert (which he terms an “unspoken ambivalence”) and overt (“we do not carry books of that type”) forms of “title selection” that help perpetuate some forms ofde facto censorship within the bookselling community.     

Intuitive ideas and scientific explanations as parts of students' developing understanding of biology: The case of evolution

Questions concerning 13–16 year old students' developing understanding of different biological concepts related to the theory of evolution of species are focused. The aim is to get more detailed examples of the ways in which students understand complex biological concepts and the development of these concepts. Data were collected from two different periods: at the beginning of the seventh and at the end of the ninth grade of the Swedish compulsory school. The examples given show how students, in various ways, construct and develop their understanding of animal and plant adaptation to nature, with the help of their biological knowledge as well as by alternative and more intuitive ideas about the function of nature. The varying abilities of students to express their ideas are discussed as well as different arguments concerning the student's difficulties in adapting to scientific ideas from more intuitive ideas.     

Conflict and Its Resolution in Small Groups of One- and Two-Year-Olds

48 1- and 48 2-year-olds were observed in groups of 3 for 25 min on 2 consecutive days, once with ample resources and once with scarce resources. The triads were composed of either 2 girls and a boy or 2 boys and a girl, and duplicate copies of toys were available for half the groups. Their conflicts contained interpersonal features and were more affected by social influences than by the availability of resources. Contrary to expectations, scarcity of resources did not result in increased conflict. In fact, 2-year-olds were more likely to resolve conflict by sharing when toys were scarce. The provision of duplicates decreased the probability of conflict, but many conflicts occurred even when a duplicate was easily accessible. The form of conflict depended on the children's age and the gender composition of the group. Older children and groups dominated by boys, relative to younger children and groups dominated by girls, were less likely to use force and more likely to resolve disputes in prosocial ways. Taken together, these findings provide further evidence for the social nature of conflict in the first few years of life.     

Teachers’ beliefs about issues in the implementation of a student-centered learning environment

Teachers’ implementation of technology-enhanced student-centered learning environments (SCLEs) will be affected by their beliefs about effective practices. In order for student-centered programs to be used as intended, designers must be aware of the key issues that will shape their implementation and the beliefs teachers hold about these issues. This case study examined 15 teachers’ beliefs about student-centered learning as they implemented Alien Rescue, a computer-based program for middle school science that was designed to create a SCLE in the classroom. Considerations for the design of similar programs are offered.     

Two conceptions of fraction equivalence

Educational Studies in Mathematics - In this study, we present a mathematical analysis distinguishing two conceptions of equivalence: proportional equivalence and unit equivalence. These two...     

碘催化丙酮缩-1,2-丙二醇的合成

以单质碘为催化剂用于缩酮的合成。研究了催化剂用量、酮醇摩尔比及带水剂用量对反应产率的影响。当0．1mol丙酮与0．12mol 1,2-丙二醇的混合物在50mg碘催化下，以环已烷为带水剂，回流分水50min，产品收率可达49％。     

吊索训练对高水平足球运动员平衡能力、踢球速度和躯干(肌肉力量)稳定性的改善

研究目的:通过量化的数据,确定以稳定性为核心的吊索训练计划(SET)对高水平足球运动员身体位置平衡能力、踢球速度和力量的作用.